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.

Complex, Specific Training Improves Sports Performance

Introduction
It is much more difficult to improve the physical performance of highly trained athletes than of previously untrained subjects. Thus, it is noteworthy that the study described below by Alves et al. (Journal of Strength and Conditioning Research, vol 24, no 4, pages 936-941, 2010) produced significant performance improvement among elite young Portugese soccer players using brief exercise sessions once or twice per week.

Experimental Method
23 young elite soccer players underwent the following tests before and after an 8-week period:

• vertical jump from a static, bent-knee position
• vertical jump using a dynamic countermovement (natural quick knee bend)
• 5 meter sprint
• 15 meter sprint
• soccer agility test

All subject initially did 2 weeks of general weight training before being divided into 3 experimental groups that did the following for 6 weeks in addition to their normal soccer training:

Group 1 - Once a week, before their regular soccer training session, they went through the following 3 exercise stations:

1. 6 reps of squats with 85% of max weight, 5 meters of high-knee skipping, 5 meter sprint
2. 6 reps of calf raises with 90% of max weight, 8 vertical jumps, 3 soccer-ball high-head hits
3. 6 reps of knee extension with 80% of max weight, 6 jumps from seated position, 3 60-cm drop jumps

Group 2 - The same routine as Group 1, but done twice a week instead of once a week.

Group 3 - Control group - did no exercises supplementary to their regular soccer practice.

Results:
5-meter sprint time improved 9% for Group 1 and 6% for Group 2
15-meter sprint time improved 7% for Group 1 and 3% for Group 2
vertical jump from static bent-knee position improved 13% for Group 1 and 10% for Group 2
none of the groups improved significantly in the countermovement jumps or agility test
the control group did not improve in any of the tests

Conclusions
A relatively short exercise program of weight-lifting, jumping, and sport-specific movements performed once or twice per week can significantly improve the physical performance of elite athletes. Even though the results of the once per week and twice per week exercise groups did not differ significantly, it appears that the subjects responded better to doing the program once per week rather than twice per week when regular sport training was persued concurrently.

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.