28 April 2011

Chocolate milk improves exercise recovery and athletic performance?

Competitive athletes need to recover quickly from bouts of training as well as competition to prepare for subsequent events.  Studies have shown that postexercise consumption of carbohydrates and protein results in better recovery than consumption of carbohydrates alone.  Postexercise supplementation is important both for restoring muscle glycogen levels and also for attenuating muscle damage for better recovery.
One question, however, for athletes is whether or not consumption of protein and carbohydrates after exercise actually results in improvements in athletic performance.  To answer, this question, a recent study was published in the Journal of Strength and Conditioning Research [1].

In this study, the authors compared supplementation in the form of chocolate milk (protein and carbohydrate) with isocaloric carbohydrate and placebo supplements in 10 cyclists.  The ten cyclists first performed 3 trials at 70% of their Vo2 max for 1.5 hours followed by 10 minutes of intervals.  After, they ingested supplements immediately post exercise, then 2 and 4 hours later.  Post recovery, the cyclists then performed a 40 km time trial (after 4 hours of rest from the glycogen depletion phase).

Ultra low-fat chocolate milk has been studied previously and compared favorably to other carbohydrate and protein supplements.  In this particular study, the actually used Kirkland organic low-fat chocolate milk from Costco.

Supplementation protocol:
  • The amounts of supplement provided were stratified according to body weight ranges.
  • Subjects weighing 63.6 kg (140lb) received 500 mL per supplement (395.25 kcals each), totaling 1,000 mL and 790.5 kcals during the recovery period.
  • Subjects weighing between 63.6 kg (140 lb) and 77.2 kg (170 lb) received 600 mL per supplement (474.3 kcals), totaling 1,200 mL and 948.6 kcals during recovery.
  • Subjects weighing 77.2 kg (170 lb) received 700 mL per supplement (553.35 kcals), totaling 1,400 mL and 1,106.7 kcals during recovery.
  • For the CHO treatment, the amount of fat matched that of the CM as measured for the individual’s weight range.
  • Overall, the CM treatment provided an average of 1.9 g CHO, 0.6 g PRO, and 0.3 g fat per kg body weight. The CHO treatment provided an average of 2.5 g CHO and 0.3 g fat per kg body weight.
Results:

The time trial performance was significantly shorter with chocolate milk supplementation when compared to either placebo or carbohydrate supplementation.  This equated to times of roughly 80 minutes vs. 86 and 85 respectively.  Even considering the prior glycogen depletion phase, an 80 minute time trial performance for 40 km is still an exceptionally slow pace for even a recreational cyclist.

Average power output was also consequently higher with chocolate milk supplementation.

Conclusions:
The key finding of this study is that a popular dairy beverage containing both CHO and PRO (low fat CM) was more effective in improving cycling TT performance in a subsequent bout compared to an isocaloric CHO or a PLA supplement.
For cyclists or other athletes, the authors also note that the novel finding of this study is that low-fat chocolate milk is widely commercially available.  When you’re travelling and competing in different events, you can pretty much buy low-fat chocolate milk nearly everywhere.

By: Dr. Jarret Morrow
Source: http://www.jarretmorrow.com

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