Effectiveness of Different Kinds of Strength Training Periodization

Periodization of strength training entails changing over time the weight handled in each exercise along with the number of repetitions per set. When the weight used is higher, the number of repetitions is lower and when the weight used is lower, the number of repetitions is higher. It is widely agreed among strength and conditioning professionals that periodized strength training is more effective than non-periodized training.

There are various versions of strength training periodization, including:

• Traditional periodization - The trainee starts with relative light weights and high repetitions, and over a period of several weeks, increases the amount of weight lifted while decreasing the number of repetitions. For example, the trainee might begin by doing 10 repetitions per set with 60% of the maximum weight that can be lifted for a single repetition and progress to 4 repetitions with 80% of the max weight.
• Daily Undulating Periodization - On different days, the trainee uses a different combination of weights and repetitions. A sample schedule might be medium weight and medium reps on Monday, light weight and high reps on Wednesday, and heavy weight and low reps on Friday.
• Weekly Undulating Periodization - Weight and reps fluctuate from week to week. A sample schedule might be low weight and high reps on week 1, medium weight and medium reps on week 2, and high weight and low reps on week 3, with this 3-week pattern repeating several times.

A recent study by Apel, Lacey, and Kell in the Journal of Strength and Conditioning Research (vol. 25, no. 3, pp. 694-703, 2011) sought to determine the relative effectiveness of traditional vs. weekly undulating periodization.

Experimental Procedure
Forty-two young, physically active men were divided into three groups of 14 that trained for 12 weeks as follows:

• Control group - Performed no strength training
• Traditional periodization (TP) - Increased the resistance in a fairly linear manner from 57% of max the first week to 80% of max the final week.
• Weekly Undulating Periodization (WUP) - Started at 57% of max, but increased resistance over 3 weeks before reducing weight close to where it started and increasing it back again over 3 weeks. This was done over 3 cycles in which both the starting and ending weight for each 3-week cycle became greater than for the previous 3-week cycle, ending at 78% of max.

There were 15 different exercises selected to work the entire body. The exercises used, rest time, total exercise volume and average percent of maximum weight used were the same in both groups. There were 3 training sessions per week for the first 2 weeks and 4 per week for the remaining weeks, in which half the exercises were performed 2 days per week (e.g. Mon. and Thu.) and the other half on 2 other days per week (e.g. Tue. and Fri).

Results

• Both periodized training groups increased significantly in strength, while the control group did not.
• Increases in back squat strength were significantly greater for the TP group (54%) than for the WUP group (34%).
• Increases in bench press strength were significantly greater for the TP group (24%) than for the WUP group (19%).
• Increases in pull-down strength were significantly greater for the TP group (29%) than for the WUP group (19%).
• Increases in dumbbell shoulder press strength were significantly greater for the TP group (48%) than for the WUP group (36%).
• Increases in leg extension strength were greater for the TP group (39%) than for the WUP group (27%), although the between-group difference did not reach statistical significance.
• There was more muscle soreness and fatigue reported among the WUD group, which may have hindered training progress.

Bottom Line
For this group of recreationally active males, traditional periodization produced superior results to weekly undulating periodization. The between-group differences were great enough to be meaningful.

Is Cycling Actually Detrimental to Bone Health?

An article by Nichols and Rauh in the Journal of Strength and Conditioning Research (vol. 25, no. 3, March, pp. 727-734, 2011) showed that hours of weekly bicycling exercise, in the absence of weight-resisted or impact exercise may actually be worse for bone density than no exercise at all. While such exercise seems fine for keeping the heart, lungs, and circulatory system healthy, and bodyweight under control, the evidence shows that it is a poor exercise for bone health.

Experimental Procedure
The study tracked, over a 7-year period, bone density in the lumbar spine, total hip, and femoral neck (segment of the thigh bone adjacent to the pelvis) as well as body fat and lean tissue measurements of 19 Master’s competitive cyclists and 18 non-athletes, who averaged 51 years of age at the start of the study.

Results

• At both the initial and final testing, the cyclists had consistently lower bone mineral density at all sites measured than the non-athletes.
• After statistical adjustment for changes in body mass index, lean mass, calcium intake and exercise habits, the cyclists lost more bone mineral density over the 7 years than the non-athletes.
• The subjects who reported doing weight-bearing or impact exercise lost significantly less bone density in the spine and femoral neck than those who did not do such exercise.
• At initial testing, 84% of the cyclists and 50% of the non-athletes met the criterion for osteopenia (subnormal bone density).
• At the final testing, 90% of the cyclists and 61% of the non-athletes met the criterion for osteopenia.
• Six of the cyclists but only one of the non-athletes had full-blown osteoporosis (critically low bone-density) by the end of the study.
• Even when they were made aware of bone-density problems, very few of the subjects changed their diets to include more calcium.

Bottom Line
The evidence provides a strong indication that cycling is not beneficial to bone health. If done in the absence of weight-resisted exercise (e.g. squat, deadlift) or impact exercise (e.g. running, gymnastics, dance) bone loss is likely to result. One hypothesis is that the lack of impact or weight on the bone fails to stimulate mineralization, while calcium-containing sweat is lost during heavy cycling exercise. Another possibility is that endurance exercise tends to suppress testosterone, which helps maintain bone mass. Older competitive cyclists are at great risk for bone fracture because of their low bone density and high risk of bicycle crashes. Weight-resisted or impact exercise should be started when people are young because that is when bone is most readily mineralized.

Active vs. Passive Recovery Between Exercise Bouts

Active recovery between bouts of exercise involves the performance of low-level exercise rather than rest, while passive recovery involves rest only. Opinions vary as to whether active or passive recovery produces better performance on subsequent exercise bouts. Two articles in the January 2011 issue of the Journal of Strength and Conditioning Research ( vol. 25, no. 1) address this issue.

The first article, by Toubekis et al. (pp. 109-116), examined the effects of passive and active rest on repeated swim sprint speed:

Experimental Procedure
10 male competitive swimmers averaging 18 years of age performed eight 25-meter swim sprints separated by 2 minute recovery periods. After the last 25-m sprint, a 6 minute recovery period was provided before a single 50-meter sprint. On different occasions each subject’s recovery periods were as follows:

• A - passive rest
• B - swimming continuously at 40% of the maximum velocity they could sustain for 100-m.
• C - swimming continuously at 60% of the maximum velocity they could sustain for 100-m.

The 25-m sprints took in the range of 11.5-13.0 seconds to complete.

Results:

• Statistically, the passive recovery and 40% of max speed recovery produced significantly faster 25-m times than did the 60% of max speed recovery.
• The average 25-m time with the passive recovery was faster than the time with the 40%-max recovery. However, the difference did not reach statistical significance.
• There was no statistically significant difference between recovery methods for the 50-m sprint.

The second article, by Miladi et al. (pp. 205-210) examined the effects of recovery by passive rest, active rest, and dynamic stretching on 4-minute work bouts and subsequent stationary bicycling time to exhaustion.

Experimental Procedure:
10 soccer athletes averaging 26 years of age exercised on a stationary bicycle at high intensity (20% higher than the power output they exhibited at their maximal rate of oxygen uptake) 4 times for 30 seconds, with 30 seconds of passive rest in between for a total of 3.5 minutes. They then had a 4 minute recovery period before doing another 3.5-minute exercise bout of the same kind. Following another 4-minute recovery period, they then cycled as long as they could at the same high intensity used in the exercise bouts. On three different occasions the 4-minute recovery periods consisted of:

• passive recovery: no exercise
• active recovery: they kept cycling, but at low intensity (30% of the power output at their maximal rate of oxygen uptake)
• dynamic stretching using 4 different lower body stretches, each done for 30 seconds. Between the stretches, "dynamic awakening" muscular exercises were done.

Results

• Dynamic stretching and active recovery both resulted in significantly longer time until exhaustion (~20%) than passive recovery.
• Dynamic stretching resulted in about 8% longer time until exhaustion than active recovery, but the difference didn't reach statistical significance.

Bottom Line
The first study indicates that passive recovery or low-intensity active recovery were most effective for 2-minute recovery periods separating 11.5-13.0 second bouts of swim sprinting. However, the second study found that stretching or active recovery was more effective than passive recovery following 3.5 minute work bouts separated by 4-minute recovery periods. The main difference between the studies lies in the duration of the work bouts and rest periods. The activities also differed - swimming and cycling.

Looking at the results of these two studies and the results of similar studies, it appears that for short sprints (under 20 seconds) and short rest periods (under 3 minutes) passive recovery is most effective, allowing short-term energy stores in the muscles to replenish. However, for longer sprints and longer recovery periods, active recovery or dynamic stretching may be more effective.

Since the effectiveness of a recovery method depends on sprint duration, recovery interval, and type of activity, it seems best for coaches to try the different recovery methods to see which one is most effective for their specific sport program.

13 Iowa Football Players with Rhabdomyolysis: A Case of Coaching Incompetence

Thirteen University of Iowa football players were recently hospitalized for rhabdomyolysis caused by extreme physical exertion. Symptoms of the ailment include dark-colored urine, fatigue, muscle weakness, and muscle tenderness. Although the athletes have since been released from the hospital, information has not been released as to whether any permanent injury has resulted.

Rhabdomyolysis is a serious medical problem. It occurs when myoglobin leaks out of muscle cells due alcoholism, crush injuries, heatstroke, extreme physical exertion and other causes. Just as hemoglobin in red blood cells carries oxygen to the muscles and other body tissue to provide energy through oxidation of carbohydrates and fats, myoglobin carries oxygen within the muscle cells to the mitochondria, which are the oxidative energy-production units within the cells. Myoglobin is a large molecule and, when it leaks into the blood stream, it travels to the kidneys for removal. However, the myoglobin molecules are too large for the kidneys to readily clear, and can easily block the kidney’s filtration system. In addition, myoglobin breaks down into potentially harmful compounds. Permanent kidney damage or even kidney failure may result, which may require lifelong dialysis or a kidney transplant. See the National Institutes of Health for further information on rhabdomyolysis.

Extreme muscle soreness brings with it with a significant risk for rhabdomyolysis. Virtually all muscle soreness is attributable to the eccentric phase of exercise, which occurs when the muscle is lengthened while resisting. This occurs in the lowering phase of every weightlifting or calisthenic repetition, and also in the initial ground-contact phase of running, particularly downhill running. It also occurs during the deceleration phase of sports activities, as in braking for directional change and bringing a moving limb to a halt.

There is no excuse for any strength and conditioning coach to induce rhabdomyolysis. The press has reported that the workouts of the Iowa football players were extremely severe and may have been used as a punishment. One athlete said, “I had to squat 240 pounds 100 times and it was timed. I can’t walk and I fell down the stairs.” Another one said, “Hands Down the hardest workout I’ve ever had in my life!”. In addition, the severe workout occurred just after the athletes returned from winter break, during which most of them had not engaged in heavy resistance exercise. That made them particularly vulnerable to extreme muscle soreness and rhabdomyolysis.

Such an approach is totally unnecessary. Firstly, exercise should never be used as a punishment. Secondly, any knowledgeable and competent coach has to be aware that any exercise regimen that induces extreme muscle soreness presents a significant risk for rhabdomyolysis. Muscle soreness is not a prerequisite for muscle strengthening! The most effective way to increase strength is to start with light resistance and gradually increase the weight lifted over a period of time as the muscles strengthen. High repetitions are totally unnecessary for strength and power athletes like football players. Muscle fatigue following a workout is expected and desirable within limits, but muscle soreness is unnecessary and can actually slow down progress in strength development.

An extensive article and interview of coaches, doctors, and a parent of one of the players is available on the Internet.

Does Heavily Advertised Exercise Equipment Really Provide Advantages?

Advertisements on TV and elsewhere make it appear that, if you buy the latest innovative exercise device you will make faster and greater gains than you could using more conventional exercise equipment. Unfortunately, such claims, however seductive, do not usually stand up to scrutiny. The following articles in the December 2010 issue (vol. 24, no. 12) of the Journal of Strength and Conditioning Research highlight instances in which such equipment fails to provide any training advantage over standard exercises.

An article by Youdas et al. (pp. 3552-3562) compared the electrical activity of 4 chest, arm, and shoulder muscles of 20 subjects doing pushups using the Perfect-Pushup device and the same subjects doing standard pushups. The Perfect-Pushup device allows free horizontal rotation of the hands during the pushup movement while, during the standard pushup, the hands maintain their position throughout the movement. Pushups both with and without the device were done 3 different ways - using wide, shoulder-width, and narrow hand placements. While the results showed some small advantages of either the Perfect-Pushup or standard pushup as to the intensity of involvement of specific muscles when using particular hand positions, neither the Perfect-Pushup nor standard pushup showed any overall superiority to the other form of exercise. Hand position had a much more striking effect on muscle involvement, indicating that pushups should be done at various hand placements in order to stimulate a wide range of chest, shoulder, and arm musculature.

Another article by Youdas et al. (pp. 3404-3414) compared exercise using the Perfect-Pullup device to standard pull-ups (overhand grip) and chin-ups (underhand grip) using an overhead straight bar. The Perfect-Pullup device allows free horizontal rotation of the hands during the pull-up movement while, during the standard pull-up and chin-up, the hands maintain their position throughout the movement. Muscle electrical activity sensors were used to monitor the effort of 7 different muscle groups for 21 men and 4 women during the exercises. The results showed that, while there were some significant differences in muscle activation between the chin-up and pull-up, there were no significant differences between the Perfect-Pullup device and either the chin-up or pull-up. The authors concluded that the Perfect-Pullup device did not provide any advantage over standard pull-ups or chin-ups.

An article by Willardson et al. (pp. 3415-3421) compared the electrical activity of 3 abdominal muscles and 1 set of back muscles during 3 traditional trunk exercises and abdominal exercise using a device called the Ab Circle. Results showed no statistically significant differences in muscle activity between the Ab Circle and standard exercises. Yet the mean activity of the rectus abdominis muscles (6-pack) and lower abdominal stabilizer muscles was highest during the standard crunch, and the erector spinae (low back) muscles and external obliques (lateral waist) were most active during the side bridge. Thus the Ab Circle provided no advantage over standard calisthenic exercises for working the abdominal and low back musculature.

An article by Schoffstall, Titcomb, and Kilbourne (pp. 3422-3426) compared the electrical activity of 5 muscles involved in abdominal and hip flexion (upper rectus abdominis, lower rectus abdominis, internal obliques, external obliques, and rectus femoris) during the following isometric exercises:
- Crunch
- Supine V-up (while facing upward, back and legs rise off the ground to make a V-shape)
- Prone V-up (while facing down, butt rises up while hands and feet approach each other, making inverted V-shape) done as follows:

• Feet on ground (no equipment)
• Feet on FB large exercise ball
• Feet on Power Slide
• Feet supported by TRX suspension straps
• Feet on Power Wheel

The results showed that:

• All exercises stimulated the external obliques, upper rectus abdominis, and lower rectus abdominis similarly
• The supine V-up without equipment showed greater internal oblique activity than the V-up done on the slide board.
• The rectus femoris was less active during the crunch than during any of the other exercises. This is not surprising since the knees are specifically bent during a crunch to take the hip-flexors out of play and focus only on the abdominal muscles.
• Overall, the prone and supine V-up exercises done without equipment provided as much training stimulus to the muscles tested as did the prone V-up using any of the commercial equipment.

Bottom Line
These studies indicate that much of the exercise equipment heavily marketed to the public provides no advantage in training stimulus over standard exercises. The only advantage of such equipment is that it provides variety, which may be important to maintain the motivation to exercise. Some exercise enthusiasts, even when informed that such equipment usually provides no shortcuts to the results they desire, may still wish to purchase them in order to keep their workout fresh, and that is fine. However, for those who would rather use their money for different purposes, there are other ways to add variety to a workout. Using standard gym equipment, a wide variety of exercises can be performed, especially using free-weight barbells and dumbbells and an overhead bar for hanging exercises.

Is Resisted Sprint Training Effective?

Coaches in sports requiring  high acceleration and all-out sprint speed have increasingly endorsed sprint training resisted by a variety of means including weighted vests, towed weighted sleds, long elastic cords, or straps for towing another individual. Yet there have been few studies examining the effectiveness of such training. A recent study by Clark et al. in the Journal of Strength and Conditioning Research evaluated the effectiveness of two types of resisted sprint training.

Experimental Procedure
There were 3 groups of  collegiate lacrosse players that trained twice a week for 7 weeks as follows:

• Weighted Sled: 7 of the subjects trained while towing 10% of their bodyweight in a sled
• Weighted Vest: 6 of the subjects wore vests containing 18.5% of their bodyweight
• Unresisted: 7 of the subjects did not use any resistance device during their training

For all groups, each training session consisted of 7-10 sprint intervals of 20-60 yards (18.3-54.9 m) separated by rest intervals of 3-4 minutes. Both before and after training, all subjects were tested as to their sprint-speed over 40 yards (36.6 m) after a 20-yard (18.3 m) running start.

Results
For the subjects as a whole, there was significant reduction (-1.1%) in the time taken to sprint 40-yards. However, there was no significant difference in improvement between any of the training groups. However, the percentage of improvement of the unresisted training group (-2.0%) was greater than for the weighted sled group (-0.1%) or the weighted vest group (-1.2%).

Bottom Line
The fact that the number of subjects in each group was relatively low made it difficult to obtain statistically significant differences in improvement between groups. However, it does appear that the resisted training was no more effective than unresisted training for improving 40-yard sprint speed following a running start. Because the timed portion of the sprints followed a running start in this study, the results do not address the effectiveness of resisted sprint training for improving the initial acceleration phase of a sprint.

Estimating the Caloric Cost of Running or Walking

A recently published article by Loftin et al. in the Journal of Strength and Conditioning Research (vol. 24, no. 10, pp. 2794-2798, 2010) measured the caloric consumption per mile of 19 normal-weight walkers, 11 overweight walkers, and 20 marathon runners. The subjects were about evenly divided among males and females.

Results

• Caloric consumption was more related to lean body mass than to total body mass
• Men burned more calories per mile than women
• Men and women did not differ in calories consumed per mile per unit body mass
• In terms of calories per mile per unit body mass, marathon runners burned significantly more than normal-weight walkers who burned significantly more than overweight walkers

The following equation was developed from the experimental data to predict an individual’s caloric consumption per mile:

Men weighed in kilograms:

Calories per mile = (0.789 x kg body mass) + 43.5

Men weighed in pounds:
Calories per mile = (0.3586 x lb body mass) + 43.5

Women weighed in kilograms:

Calories per mile = (0.789 x kg body mass) + 35.8

Women weighed in pounds:
Calories per mile = (0.3586 x lb body mass) + 35.8

Bottom Line

The equation can be useful for those interested in estimating the caloric cost of their walking or running workout.

The Drawback of Exercising on Unstable Surfaces



Stability training, mainly in the form of lifting weights while standing on unstable surfaces, became somewhat popular with the advent of the Bosu Ball, which is a hemispheric ball about 2+ feet across mounted on a flat plastic base. The idea is that the instability of the surface brings muscles into play that are required for maintaining stability; muscles that would be minimally involved when exercising on a stable surface.

A study by Chulvi-Dedrano et al. in the Journal of Strength and Conditioning Research (vol. 24, no. 10, pp. 2723-2730, 2010) tested force production and muscle electrical activity during deadlifts on a stable surface and on two different unstable surfaces.

Method
31 young adult subjects did the following:

1. Isometric deadlift in which the lifter pulled upward maximally for 5 seconds against an immovable bar
2. Dynamic deadlift in which a barbell weighing 70% of the individual’s maximal isometric deadlift was lifted for 5 repetitions 

Lifting force was measured during the isometric efforts. Muscle electrical activity of the lower back muscles (paraspinals) was measured during both the isometric and dynamic lifts to indicate how hard the muscles were working. Both of the lifts were done on the following 3 surfaces:

1. Stable floor
2. Bosu Ball
3. T-Bow (a curved board that can rock laterally as one stands on it)

Results

• In the isometric deadlift, both the force produced and the muscle electrical activity were significantly higher on the stable surface than on either unstable surface.
• In the dynamic deadlift, muscle electrical activity was significantly higher on the stable surface than on either unstable surface

Bottom Line
This study backs up other ones that have shown that exercising on unstable surfaces does not provide as much stimulus as stable-surface training to the main muscles (prime movers) used to effect the exercise movement. It has previously been shown that more weight can be handled when lifting on stable than unstable surfaces, providing greater stimulus to the muscles. In view of these factors, training on unstable surfaces is not best for increasing the size or strength of the major muscles. However, since such training does bring stability muscles into play, it can be effectively used as a supplement to training on stable surfaces, especially for athletes who engage in sports in which maintaining stability is of major importance (e.g. hockey, figure skating, snow-boarding, gymnastics). The major part of the resistance workout should still be on stable surfaces.

Dynamic Stretching Beats Static Stretching for Team Sports

Introduction
Static stretching involves attaining a stretch to the point of mild discomfort and holding the position for at least 10 seconds. Dynamic stretching involves rapid repeated alternation between a stretched and a relaxed position.

A recent article by Amiri-Khorasani et al. in the Journal of Strength and Conditioning Research (vol. 24, no. 10, pp. 2698-2704, 2010) showed that static stretching detracts from performance on a physical agility test, while dynamic stretching tends to improve it.

Method
Nineteen professional soccer players were divided into more-experienced and less-experienced subgroups. Their performance on an agility test, which involved 14-15 seconds of changing direction and zigzagging as fast as possible around a number of cones, was tested after each of the following:

• No stretching
• Static stretching
• Dynamic stretching
• Combined static and dynamic stretching

Results

• The subjects were 4-5% slower after static and combined static/dynamic stretching than they were with either no stretching or dynamic stretching alone.
• Among the less-experienced players, dynamic stretching resulted in about 3% faster course times than no stretching.
• Among the more experienced players, there was no difference between the course times after dynamic stretching and no stretching.

Bottom Line
The evidence indicates that dynamic stretching is superior to static stretching for the kind of agility needed for most team sports. This is probably due to a reduction after static stretching in the spring-like stiffness of muscle. The results support those of other studies that have shown a detrimental effect of static stretching on strength, jumping ability and sprint speed. It is not clear why the experienced players in this study showed no advantage of dynamic stretching over no stretching at all. However, since these were professional soccer players, it seems safe to conclude that the effects on amateur athletes would parallel those on the less experienced professional players. Thus, their performance would likely be enhanced by dynamic stretching.

Plyometric Training for Improved Sports Performance

Plyometric training has been popular among strength and physical conditioning coaches for a number of years. Yet many people who exercise on their own are not familiar with this method. Simply put, plyometric exercise involved rapid stretch and shortening of a muscle. This occurs in such movements as hopping, jumping, and bouncing. For example, when you jump vertically, you naturally first do a countermovement in which you bend your knees quickly while stretching your quadriceps (front thigh) muscles, then rapidly contract those muscles to straighten the knees and propel the body upwards. Thus, repeated vertical jumps are one kind of plyometric exercise.

There are various gradations of plyometric exercise, and it is considered prudent to start with low-stress ones before progressing to more difficult ones. One of the most stressful plyometric exercises is depth-jumping, in which one jumps down from a box and, after contacting the ground, immediately jumps vertically. This is considered dangerous for anyone who does not already have a strong lower body and has not progressed from low-stress, through moderate-stress, to high-stress plyometric exercise. Various sources have recommended being able to squat with 1.5 times one’s bodyweight before taking on a serious plyometric exercise program. However, it is generally considered safe for people in good health without orthopedic problems to perform low-stress plyometric exercises like low bounces, hops, and jumps.

A recent study by Chelly et al. in the Journal of Strength and Conditioning Research (Vol 24, no. 10, pp. 2670-2676, 2010), showed how effective plyometric training can be.

Method
A group of experienced young male soccer players, average age 19 years, trained as follows:

• August - preseason training consisting of light resistance exercise and calisthenics
• September through March (the competitive season) - The players trained 5 days per week for 90 minutes by doing skill and tactical drills along with 30 minutes of continuous play. On one day per week they engaged in a competitive soccer game against another team.

The subjects were divided into 2 groups:

Group 1 only did the training program above.
Group 2 did the training program above plus from January-March they also did the following plyometric training twice per week:

• Week 1: 5 sets of jumping over ten 40-cm (24“) hurdles spaced 1 meter (39.4”) apart
• Week 2: 7 sets of jumping over ten 40-cm (24“) hurdles spaced 1 meter (39.4”) apart
• Week 3: 10 sets of jumping over ten 40-cm (24“) hurdles spaced 1 meter (39.4”) apart
• Week 4: 5 sets of jumping over ten 60-cm (36“) hurdles spaced 1 meter (39.4”) apart
• Week 5: 4 sets of depth-jumps from a 40-cm (24“) box
• Week 6: 4 sets of depth-jumps from a 40-cm (24“) box
• Week 7: 4 sets of depth-jumps from a 40-cm (24“) box
• Week 8: 4 sets of depth-jumps from a 40-cm (24“) box

Extensive testing on speed, power, and jump height was performed before and after the training.

Results

The group that did regular soccer training did not show significant improvement in any of the pre-post tests.

The group that did plyometric training in addition to their regular soccer training showed the following statistically significant improvements:

• Thigh muscle volume: +2.5%
• Cycle ergometer absolute power: +4.5%
• Cycle ergometer power relative to body mass: +5.9%
• Jump height without a countermovement: +8.3%
• Jump height with a countermovement: +2.5%
• 40-meter sprint first step velocity: +18.2%
• 40-meter sprint velocity over first 5 meters: +10.0%
• 40-meter sprint velocity between 35 and 40 meters: +9.8%

Bottom Line
Although not all studies of plyometric training have produced improvements of this magnitude, it appears that the evidence supports inclusion of plyometric exercise in physical training programs for sports involving sprinting and/or jumping.

NOTE: This description of experimental results is for informational purposes only and does not constitute a recommendation. Anyone engaging in an exercise program should obtain proper medical authorization before doing so.

Static Stretching Can Impair Distance Running Performance

At times it can be difficult to find sports science articles that have true relevance to athletes. But here's one that can have real impact. A study by Wilson et al. (Journal of Strength and Conditioning Research, vol 24, no. 9, pp. 2274-2279, 2010) provides strong evidence that static stretching before a distance-running event can impair performance among young, male athletes.

Static stretching involves stretching a muscle to the point of mild discomfort and holding the stretch for 10-30 seconds. We have previously highlighted previous evidence that static stretching can impair jumping performance. It has also been shown to reduce maximal leg-press strength, 20-meter sprint speed, and knee-extension torque. Yet this is the first study to examine the effect of static stretching on endurance performance.

Experimental Procedure
10 male collegiate competitive distance-runners and triathletes who ran at least 20 miles per week and were in excellent aerobic condition were tested on 2 different days, at least a week apart, after the following:

1. 16 minutes of stretching consisting of the following 5 stretches each performed 4 times for 30 seconds of holding:: 1) sit on floor with knees straight and reach with both hands to and beyond the toes, 2) stand with balls of feet on a block, letting bodyweight stretch calves, 3) for both left and right, stand on 1 leg and pull the opposite heel toward the butt 4) for both left and right, lunge deeply, and 5) cross the left leg over the right one, and pull the right thigh towards the torso, repeating for other side
2. Quiet Sitting

After stretching or not stretching, the subjects underwent the following treadmill tests:

1. Run at 65% of maximal aerobic capacity (VO2max) for 30 minutes while energy-cost is measured.
2. After 2 minutes of rest and rehydration, run as far as possible in 30 minutes (subjects could control treadmill speed and see a time display, but not see a speed or distance display).

Experimental Results
On the no-strech day, the athletes performed significantly better as follows:

• They covered an average of 6.0 km in 30 minutes on the no-stretch day compared to 5.8 km on the stretch day
• They required an average of 425 calories on the stretch day vs. 405 calories on the no-stretch day to do the 30-minute submaximal run.

Bottom Line
Static stretching before running hurt the athletes' distance-running performance. After stretching they required more energy to run the same speed in the submaximal test, while in the maximal-distance 30-minute test they were not able to run as far. These differences can easily affect the chance of winning a race. The negative effect of static stretching appears to be due to a reduction in the spring-like stiffness of the leg muscles resulting in lower efficiency. Thus, it does not appear advisable to do static stretching before distance-running events. While dynamic stretching has not been subject to similar testing, it is a possible alternative. The evidence suggests that the best warmup before a distance-running event may be walking followed by jogging followed by short-distance runs at speeds increasing to race-pace.

Mixed-Intensity Interval Training vs. Steady-Speed Running

Evidence continues to pile up concerning the advantages of interval training. A study by James Clark in the Journal of Strength and Conditioning Research (vol. 24, no. 7, pp. 1773-1781, 2010) compared interval training comprised of runs of varying lengths and intensities to steady-speed running as to which produced greater improvements in maximal oxygen uptake (VO2max), the gold standard of aerobic fitness.

Study Procedure
The subjects were 32 female league and college competitive soccer players who were divided into 2 groups that trained as follows for 8 weeks:

1) Mixed-Intensity Interval Training (MIIT): The workout consisted of repetitions of the following 6-minute exercise cycle:

• 30 sec of jogging
• 30 sec running at 90-100% of max effort
• 60 sec of jogging
• 60 sec running at 80-90% of max effort
• 90 sec of jogging
• 90 sec running at 70-80% of max effort

      The subjects did 2 cycles (12 min) the first week and increased to 6 cycles (36 min) by the eighth week.

2) Steady-Speed Training (SST): They ran steadily at a "moderate to hard" pace (heart rate corresponding to 60-80% of that at maximal oxygen uptake). Run time was 40 minutes the first week and increased to 60 minutes by the eighth week.

Results
The mixed-intensity interval training group improved in maximal oxygen uptake by over 25% while the steady-speed training group improved less than 17%, a statistically significant difference.

Bottom Line
The mixed-intensity interval training improved aerobic fitness more than did steady-speed running, and required less time per workout. In addition, while it was not tested, it is likely that the sprinting segments of the interval training produced more improvement in sprinting ability, which is essential for soccer and other sports requiring bursts of speed. Thus, it appears that mixed-intensity interval training is advantageous for athletes in various team sports. Steady-speed running is still important for distance runners, who generally work out at various intensities during a training week.

NOTE: This description of experimental results is for informational purposes only and does not constitute a recommendation. Anyone engaging in an exercise program should obtain proper medical authorization before doing so.

Grouping Exercises Saves Times While Providing Equal Benefits

The benefits of the multiple mini-circuit method of performing resistance exercise have been described previously in this blog. It involves doing a set of each of 2-5 exercises in a grouping, then repeating the cycle 3 or more times before going on to the next exercise grouping. The advantages include:

• A lot of exercise can be done in a given time period.
• Each muscle group has adequate recovery time.
• Heart rate remains high, affording some aerobic conditioning.
• The body becomes accustomed to intermittent high-intensity exertions, relevant to many sports.

A recent article by Robbins at al. in the Journal of Strength and Conditioning Research (vol. 24, no. 7, pp. 1782-1789, 2010) provides research support for this exercise method.

Study Method
18 physically trained men performed the following two exercises:

• Bench Pull - lie face down on a bench and perform a rowing movement to raise a barbell lying under the bench
• Bench Throw - Perform an explosive bench press movement throwing the bar upwards, using a specially designed machine that catches the barbell so it does not fall back down on the lifter

On one day they first did 3 sets of bench pulls followed by 3 sets of bench throws for a total of about 20 minutes of exercise. On another day, they alternated sets of bench pull and bench press, accomplishing 3 sets of each, for a total of about 10 minutes of exercise.

Results
Even though the alternating sets took half as much time as performing 3 sets of one exercise followed by 3 sets of the other exercise, the subjects were able to handle as much weight for as many repetitions of each exercise in both types of routines. In addition, measures such as bench press throw height, peak power, peak velocity, and muscle electrical activity were the same for both routines.

Bottom Line
While saving a lot of time, performing exercises in groupings worked the muscles as well as doing all sets of each exercise before going on to the next exercise. Thus, the grouping method enables a full workout to be performed in much less time or allows more work to be done in a given amount of time.

NOTE: Our descriptions of exercise programs are for educational purposes and do not constitute recommendations. Anyone embarking on a physical exercise program must be in good enough health to safely do so. Fitness to exercise can best be determined by a physician's clearance.

Can Mental Imagery Improve Physical Strength?

Mental imagery involves envisioning oneself performing a physical activity without actually doing it. It is currently used by many high-level athletes to enhance their physical performance. While the method is well-accepted for maintaining focus and consistency of technique, its use has recently been examined for improving strength as well.

Study Method
In a study by Lebon, Collet and Guillot in the Journal of Strength and Conditioning Research (vol. 26, no. 6, pp. 1680-1687, 2010) male college athletes who had not been weight training were put on a program of bench-press and leg-press training 3 times per week for 4 weeks. The only difference between the training groups was that the imagery group visualized doing each exercise during the between-set rest periods while the control group performed another thought task.

Results
Both groups improved in strength and the number of repetitions they could perform with 80% of the maximal weight they could lift during pre-training tests. However, the imagery group improved 26% in leg press strength vs. 21% in the control group. Repetitions with 80% of pre-training max increased 92% in the imagery group vs. 79% in the control group. Both between-group differences were statistically significant. There were no differences between training groups as to changes in bench-press performance and neither group showed any significant increases in muscle-size.

Bottom Line
It is known that the strength gains resulting from the first few weeks of training are largely due to neuromuscular adaptations rather than muscle-size increases. Mental imagery may enhance the neuromuscular component of strength change and thus the most applicable to novice lifters. It is not clear why the method was effective for the leg press but not the bench press.

Is Elliptical Training as Good as Running for Improving Fitness?

Elliptical trainers have become very popular in gyms as well as in the home. Their popularity is due to a lack of impact on the body while providing resistance to both the lower and upper body musculature. The movement pattern looks similar to running but does not involve pounding of the feet on the ground. An added advantage is the relative silence of an elliptical device compared to a treadmill, which produces considerable noise from foot strikes and its motor.

An important question is whether the elliptical trainer provides as good an aerobic workout as a treadmill or running outside. A study by Brown et al. in the Journal of Strength and Conditioning Research (volume 24, number 6, pp. 1643-1649, 2010) was designed to answer that question.

Experimental Procedure
9 male and 9 female college-aged subjects worked out for 15 minutes on different days on both a treadmill and an elliptical trainer at a difficulty level they self-selected as “somewhat hard.” The subjects were instrumented to collect information on their rate of oxygen utilization, pulse rate and other relevant variables.

Results
The only statistically significant differences between exercise on the elliptical machine and the treadmill were that the elliptical machine produced higher:

• heart rate
• percentage of maximal rate of oxygen utilization
• Ratio of carbon-dioxide produced to oxygen used

However, there were no significant differences in total energy expenditure or total oxygen consumption.

Bottom Line
The similarities between the responses to exercise on the elliptical trainer and treadmill were far more important than their differences. They both produced very similar aerobic stimulus to the body when the subjects worked out at a moderate level of difficulty, which is typical. Therefore, for general health, one can use an elliptical trainer with confidence. However, since running is a very basic human activity that is essential for sports and reacting to emergencies, run training is still generally more useful. Someone who trains exclusively on an elliptical machine and reaches a high level of fitness will not perform as well when faced with a running challenge, and muscle soreness will surely result. Yet, elliptical training is a good way to maintain cardio-respiratory function for injured athletes and others who cannot tolerate lower body impact. It can also provide variety in training for those who run regularly.

How to Avoid Weightlifting-Related Shoulder Injuries

Terms used in this article:

• Rotator cuff: Muscles (supraspinatus, infraspinatus, teres minor, subscapularis) that stabilize the shoulder joint and rotate the arm at the shoulder
• Internal shoulder rotation: Standing with your upper arm against your torso with your elbow at a right angle, rotate your upper arm inward until your hand touches your abdomen.
• External shoulder rotation: From the position you just attained by internally rotating your shoulder, rotate your upper arm outward so that your hand moves away from your abdomen, as you would when throwing a Frisbee.
• Trapezius muscle: Extends from the back of your head and neck down your central upper back and serves to raise the shoulders and draw them backwards.
• Range of motion: The number of degrees through which a joint can be rotated.

A recent article by Kolber et al. in the Journal of Strength and Conditioning Research (Vol 24, no 6, pp. 1696-1704, 2010) reviewed existing scientific research articles on shoulder injuries brought on by weightlifting. It noted that 25-35% of people who engage in resistance training sustain an injury severe enough to require medical attention and that 36% of such injuries are to the shoulder. The vulnerability of the shoulder is related to the high number of exercises that involve the shoulder, the great stresses the exercises place on the shoulder, and the unfavorable positions in which some exercises place the shoulder. In addition, many lifters do not warm up properly, select a balanced set of exercises, use proper lifting technique, or modify/eliminate exercises that cause pain. Major muscles are frequently worked to the exclusion of minor ones, leading to muscle imbalances. Shoulder muscles commonly injured include the pectoralis major, biceps, deltoid and rotator cuff group.

The Most Common Signs of Shoulder-Dysfunction Among Weightlifters:

• Reduced internal shoulder rotation range of motion
• Excessive external shoulder rotation range of motion
• Underdeveloped external rotation strength relative to internal rotation strength
• Underdeveloped external rotation strength relative to arm abduction (raising) strength
• Underdeveloped lower trapezius strength relative to upper trapezius strength
• Instability of the anterior (front) shoulder
• Tightness of the posterior (rear) shoulder

Common Pain-Producing Exercises
The following exercises in which the upper arm is raised to the side and parallel to the floor while the forearm is vertical put the shoulder in a fully externally rotated position and are considered hazardous:

• Behind the neck pull-down
• Behind the neck overhead press
• Overhead stack machine press in which the hands move rearward as the weight is lifted

Other exercises, although generally safe, also associated with shoulder pain:

• Bench press
• Incline chest fly
• Supine chest fly
• Dip
• Biceps curl

The following may help to prevent weightlifting-related shoulder injury:

• Discontinue any exercise that causes pain.
• If an exercise hurts, try variations that do not hurt (e.g. bench press with rolled up towel on chest to limit movement).
• Balance every push exercise with a pull exercise in the opposite direction.
• Balance exercises involving major body movements (e.g. bench press, pull-down) with those that stabilize and rotate the shoulder.
• Exercises that strengthen external shoulder rotation are particularly important (e.g. do the external rotation movement described above, resisted by weight stack cable or elastic band).
• Do strength exercises for the lower trapezius (e.g. rowing motions with elbows high and shoulders drawn fully back).
• Do flexibility exercises to increase internal shoulder rotation.
• Do flexibility exercises to stretch the rear shoulder (e.g. Stand with upper arm parallel to the ground. Grip elbow with other hand and pull arm horizontally across the chest).

Should You Skip Breakfast to Burn More Fat During a Workout?

An Associated Press article suggesting that, because skipping breakfast before a workout burns more fat, such a practice may be effective for body fat loss. Yet, the study on which the article is based provides absolutely no evidence that such a practice would result in a stable loss of body fat. Sure, if your body is depleted of stored carbohydrates in the form of muscle and liver glycogen, you will burn more fat during exercise. However, a close look at the article reveals that the fat burned is in the muscle, and not around the waist or other parts of the body where people generally want to lose fat. Thus, exercising in a fasted state merely depletes intramuscular fat that is replenished upon eating. So there is no net body fat loss unless one consumes fewer calories than are used, which requires dietary control. So we can’t escape from the truism that the only way to lose weight is to burn more calories than you take in.

The following are additional reasons not to exercise in a fasted state:

• You will feel less energetic and more lethargic
• The quality of your workout will diminish
• Your motivation to exercise will be reduced
• You will cannibalize muscle to convert protein into needed carbohydrates

The only advantage to running in a fasted state might be for long-distance runners who wish to train their bodies to preferentially burn fat, thereby sparing muscle and liver glycogen to avoid “hitting the wall” late in a race. However, training with long-distance runs accomplish the same goal.

Caffeine May Interfere With Muscle Building

An online article in the Journal of Sports Science and Medicine by Wu and Lin (vol 9, pp 262-269, 2010) indicates that going heavy on the caffeine before resistance training may be counterproductive.


Experimental method
Ten men performed a workout consisting of 3 sets of 8 exercises. Each set consisted of 10 repetitions of 75% of the weight that could be lifted only once. On one day, the workout was performed an hour after caffeine ingestion and on another day an hour after ingesting a non-caffeinated placebo. The amount of caffeine was 6 mg/kg or about 475 mg for a 175 lb man. That’s about the amount of caffeine in one-and-a-half 16 oz Starbucks Grande coffees or four-and-a-half 8 oz cups of home-brewed coffee. Blood was analyzed at various times for levels of insulin, testosterone, cortisol, growth hormone, glucose, free fatty acid and lactic acid.

Results
As has been observed in previous studies, blood levels of free fatty acids were higher in those who ingested caffeine than in those who did not. That is why caffeine is considered an ergogenic aid (performance enhancer) for endurance sports. Long distance runners often take in caffeine to promote the burning of fats in preference to carbohydrates, allowing the limited store of carbohydrates in the muscle and liver to last longer, sparing the athlete from “hitting the wall’ later in the race.

A result not noted in previous studies was that blood concentration of human growth hormone (HGH) was significantly lower when the subjects had previously ingested caffeine than when they hadn‘t. Since HGH is a muscle-building hormone, caffeine ingestion prior to resistance training can be considered counterproductive.

There were no significant differences in blood levels of insulin, testosterone and cortisol between caffeine and no-caffeine conditions.

Bottom Line
It appears prudent to avoid caffeine consumption for at least 3 hours prior to a resistance training session in order to maximize results. Since the time it take for the body to rid itself of half of ingested caffeine is approximately 5 hours in healthy adults, then excessive caffeine consumption is not recommended, even several hours before a workout.

Grouping Weightlifting Exercises for Time-Efficiency

The usual recommended rest period between sets of a weightlifting exercise is 1-5 minutes. Short rest periods are most often used by bodybuilders, while longer rest periods are often used by athletes looking to achieve maximum strength in specific lifts, such as those engaged in powerlifting or Olympic weightlifting competition. Most athletes and recreational lifters rest 2-3 minutes between sets.

Since the rest period between sets can account for the great majority of total workout time, some strength and conditioning coaches and athletes favor doing exercises in groups of 2-5, doing a set of each of the exercises in the group, then repeating the cycle 3 or more times before going on to the next group. The exercises within a given group involve different muscles. There is typically little time between sets but, because of the grouping system, more substantial time between sets of the same exercise. Such a routine has been called "multiple mini-circuits." The advantages of this type of program are that:

• A lot of exercise can be done in a given time period
• Each muscle group has adequate recovery time
• Heart rate remains high, affording some aerobic conditioning
• The body becomes accustomed to intermittent high-intensity exertions, relevant to many sports

The time-efficiency of such a workout is substantial. A typical weightlifting set takes about 30 seconds. If the trainee moves directly from one exercise to the next, there is generally only 30-40 seconds between the end of one set and the beginning of another. Thus, after becoming accustomed to this type of workout, a trainee can typically do 40-50 exercise sets in one hour, without sacrificing weight lifted or repetitions accomplished. In comparison, someone doing sets of the same exercise consecutively, with 2-3 minutes of rest in between, typically completes only 18-24 sets within an hour. Thus, performing exercise in groups allows one to either do twice as many exercises in a given amount of time or to take half the time to do the same number of exercises.

The exercises within a group use different movements and involve different muscle groups. A group might consist of:

1. Push: bench press
2. Pull: stack row
3. Leg: squat
4. Torso: leg raise

3-5 such groupings make for a comprehensive total-body workout. Done twice per week, this leaves time for a lot of other conditioning activities such as sport drills, plyometrics, distance running, speed work, and agility training.

The results of a research study by Robbins et al. (Journal of Strength and Conditioning Research, vol 24, no 5, pp 1237-1245, 2010) supports this type of training. In the study, following a warmup, 16 males performed 3 sets of bench press and 3 sets of bench pulls 2 different ways:

1. 3 consecutive sets of bench pull beginning 4 minutes apart, followed by 3 consecutive sets of bench press beginning 4 minutes apart, for a total workout time of 20 minutes.
2. 3 pairs of alternating sets of bench pull and bench press beginning 2 minutes apart for a total workout time of 10 minutes.

Note that both routines provided 4 minutes between sets of the same exercise. Analysis of the study results showed the two workouts similar in effect on the muscles. Both were similar in muscle electrical activity, the amount of weight lifted, and the number of repetitions performed in each set. The study also gave support for grouping more than 2 exercises together, as full recovery was not achieved with 4 minutes between sets of the same exercise.

Medical Disclaimer

This description of exercise practices and experimental results is for informational purposes only and does not constitute a recommendation. Anyone engaging in an exercise program should obtain proper medical authorization before doing so.

Making the Best Use Your Time in the Gym

I'm frequently amazed by how much time many people waste in the gym. This particularly applies weight lifters, because it is difficult to waste time when you’re on a cardio machine or in a group exercise class, both of which provide largely non-stop exercise. But lifting allows you to go at your own pace, so it is very easy to get lazy or distracted. You may have even been given the incorrect advice that a work-to-rest ratio of one to five is the right way to exercise.

I recently saw a gym patron talking on a cell phone most of the time and doing a minimum of lifting between conversations. I’ve seen many others standing around chatting for long periods. Then there are the people who do a set of exercise and sit on the bench or machine for 3-5 minutes before doing another set, oblivious to other people who are waiting to use the device. I even saw one gym patron reading magazine articles between sets. And personal trainers, who have great influence over their trainees, often chat extensively with their clients. That might be effective for promoting a client-trainer relationship, but it’s certainly not the best for physical conditioning.

Long rests between lifting sets is recommended for a very limited number of competitive strength athletes, such as Olympic weightlifters, who spend hours in the gym in their quest to maximize the weight they can lift and need long rest periods for full recovery and to focus on technique. However, such time-intensive programs are not effective for bodybuilders or athletes in most sports that require a good balance of strength, muscular endurance, and overall conditioning. It takes an inordinate amount of time to do a comprehensive workout when there is a lot of time between exercise sets. Most of us have lives outside of the gym and must work out efficiently to get the desired benefits within a limited amount of time. Even high-level athletes often must commit so much time to the practice of their sport that they do not have many hours in the week left to spend in the gym on training.

One way to do a comprehensive workout in a limited time is to work out in groups of 2-5 exercises. For example, you can first go through the following group 3 times: 1) an upper-body push exercise, 2) an upper-body pull exercise, 3) a lower-body push exercise, and 4) a torso exercise. After the first group is done, a second and then a third group of exercises are performed. While a beginner should rest as needed between sets, as one becomes conditioned , the only rest needed between sets is the time required to walk between stations and adjust the weight. Using this method, a well-conditioned lifter can accomplish more than 40 sets of exercise in one hour. Some advantages of this system are:

• There is enough rest between sets of the same exercise to allow optimal recovery time for that muscle group.
• Both strength and muscular endurance are developed
• The heart rate stays up, providing some aerobic benefit
• More calories are burned per hour.
• The routine provides whole-body conditioning essential to most sports
• The workout leaves more time to work on speed, power, agility, and endurance, as well as practice of one's sport.

Bottom Line
Time spent in the gym talking, sitting, standing around, or reading does not contribute to one’s physical development. A great majority of gym time should be spent exercising unless the gym is the center of one's social life. A routine based on cycling through groups of 2-5 exercises provides a lot of muscle work in a limited amount of time, and provides the added benefit of total body conditioning.