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Tuesday, February 8, 2011

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.

  • 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.
  • 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.

Friday, February 4, 2011

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.