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.

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.

Improving Performance in High-Level Athletes

Introduction
     It is not difficult to improve the physical performance of people who have had little or no intense training. Yet, it is much more challenging to improve the performance of high-level athletes who presumably have been training and competing at intense levels for considerable time. After all, their training and play have already stimulated their bodies to make major physiological changes, and many have likely reached a plateau by which they are no longer improving in their physical performance. However, a study by Wong et al. in the latest issue of the Journal of Strength and Conditioning Research (vol 24, no 3, 2010, pp. 653-660) shows that even the performance of professional athletes can be improved by a well-designed training program.

Experimental Methods
A group of Hong Kong professional soccer players were divided into 2 groups that trained for 8 weeks during the pre-season as follows:

• Group 1: made up of 20 players who engaged in strength training and high-intensity interval training twice per week in addition to their regular soccer training. The strength training consisted of 4 sets of 6 repetitions of high pull, jump squat, bench press, back half squat, and chin-up. The high-intensity intervals consisted of sixteen 15-second sprints at 20% faster than maximal aerobic speed interspersed with 15-second rest periods. The method for determining maximal aerobic speed was not clearly described. However, it might be taken as the fastest pace at which one can run 3-5 miles (5-8 km).
• Group 2: made up of 19 players engaged in only their regular soccer training.

Results
Only Group 1 improved significantly in the vertical jump (by 4%), 10-meter sprint time (by 6%), and 30-meter sprint time (by 3%).
Group 1 improved twice as much (20%) in a test of shuttle-running at progressively increasing speed as Group 2 (9%).

Bottom Line
Even high-level athletes can improve their physical performance by following a well-designed training program. Twice per week sessions of high-intensity interval training and weight training in addition to regular sport training appear effective for high-level athletes. It should be noted that this was pre-season training. Generally, during a competitive season, exercise other than regular sport-drills and competition is cut back considerably to avoid overtraining.

Medical Disclaimer
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.

Longer-Interval Run Training Shows Beneficial Cholesterol Effect

Introduction
The two major fractions of blood cholesterol are low-density-lipoprotein (LDL) cholesterol and high-density-lipoprotein (HDL) cholesterol. LDL increases the risk of heart-disease because it is readily deposited in arterial walls and can result in a blood clot that shuts off the blood supply to the heart muscle. In contrast, LDL removes cholesterol from arterial walls. The ratio of total cholesterol (TC) to HDL cholesterol is a risk-index for heart-disease. The higher the ratio, the greater the risk. The average ratio is 4.5, but doctors recommend it be below 4.0 and preferably below 3.0.

Endurance exercise has been shown to improve the TC/HDL ratio, but interval training (sprint running interspersed with rest periods) has not been shown effective in this regard. However, a recent study by Musa et al. (Journal of Strength and Conditioning Research, vol 23, no 2, 2009, pages 587-592) showed that interval training using longer running intervals (500 meters ~ half-mile) can be effective for improving the ratio.

Experimental Procedure
20 college age males ran 4 half-mile intervals at high intensity (90% of max heart rate) seperated by rest periods equal in time (3-5 min) to the running intervals, 3 times a week for 8 weeks. Their TC/HDL ratio improved by 18%, reducing their risk of heart-disease by an estimated 37%. The training also improved their 2.4 km (1.5 mi) running time by 9%.

Bottom Line
Interval training using running distances of 0.5 miles and rest periods equal to run time can effectively enhance blood cholesterol profiles, reducing risk for heart-disease. Thus, for individuals healthy enough to withstand the strain of high-intensity running, longer-distance interval training can have a valuable place in a physical fitness program.

The Magic of Interval Training

The evidence continues to mount that interval training is very effective in a number of ways. For those not familiar with interval training, it involves short bouts of intense exercise (usually running, cycling or rowing) interspersed with longer periods of light exercise. An example involving running would be to warm up thoroughly first, then run a quarter-mile (~400m) at 85-90% of max speed, then walk or jog an eighth-mile (~200 m), repeating the run/walk cycle for 8-10 repetitions followed by a warm-down. There are many variations of interval training, and some involve even shorter bursts of intense exercise (e.g. 200m runs).

A recent article in the Journal of Strength and Conditioning Research (Tanisho and Hirakawa, vol 23, no. 8, 2009, pages 2405-2410) reinforces the efficacy of interval training. The subjects were 18 Japanese male lacrosse players who trained 3 days/wk for 15 weeks on an exercise cycle. The continuous-training (CT) group pedaled continuously for 20-25 minutes, while the intermittent-training group (IT) alternated 10-second max-speed pedaling with 20-second easy pedaling, for a total of 10 intervals (total time = 5 minutes). There was also a control group that did no training. Interestingly, the IT group improved almost as much (10%) in the maximal oxygen uptake test (gold standard of aerobic fitness) as the CT group (12%). However, only the IT group improved in maximal power output. The IT group was also the only one to improve in fatigability, measured as the ability to maintain cycling power output over 10 intervals of 10-second max-speed pedaling interspersed with 40-second recovery periods.

One would have to conclude that the interval training produced amazing results. The 5-minute interval training sessions produced almost as much increase in aerobic capability as 20-25 minutes of endurance training. Yet the interval training also produced significant gains in maximum power and in resistance to fatigue from repeated intense exertions bouts. IT was a truly remarkable and time-efficient form of training.

This type of training is clearly advantageous for most team sports, which generally involve short bursts of intense activity interspersed with mild-to-moderate activity. The effectiveness of the interval training supports the concept of Specificity of Training, by which training is most effective when it reflects important aspects of the sport in which improvement is sought. Distance running is not effective for most team-sport athletes because it has been shown to actually reduce max power output, needed for jumping and sprinting. Thus long runs are only recommended for athletes in endurance sports.

A word of caution is in order. No-one should engage in an exercise program without first determining whether a doctor's clearance is needed first. See our Exercise Risk Questionnaire. Even if you are cleared for general exercise, you may not be ready yet for interval training, which should only be undertaken by people who are already well-conditioned. It is an intense form of exercise that puts considerable strain on the heart, lungs, muscles, and bones. Running intervals can easily cause muscle pulls or other musculoskeletal injuries, so very thorough pre-interval warmups are necessary. Cycling and rowing intervals involve less impact and peak force on the musculoskeletal system than running and are thus less likely to produce injury. However, any interval training must be approached with caution. The key points are to start with a well-conditioned individual, warm up very thoroughly, and start at a moderate level of difficulty, increasing the intensity of intervals over a period of several weeks.