Friday, February 13, 2015

Milk & Exercise a Perfect Match? A Summary of the Latest Scientific Studies on Its Ability to Sustain Muscle Growth, Protect from Muscle Damage, Binges and Dehydration

Is milk the perfect fluid replacement + anti-post-workout binge + muscle protector for gymrats, fitness junkies and professional athletes? 
It stands out of question. Compared to Coke and many of the so-called "sports-" or "energy drinks" that are in fact no much more than over-caffeinated liquid sugar bars, milk is a healthy beverage. Whether it's also a potent ergogenic though, is still intensely debated.

A recent study from the McMaster University in Hamilton, Ontaria, for example, indicates that the initial surge in post-workout protein synthesis cannot be sustained solely by the low amount of protein in regular milk (Volterman. 2015). Its inability to trigger longlasting increases in protein synthesis and thus to promote a positive whole body protein balance does yet not negate the already proven benefits milk and some of its less-known constituent (I am not talking about whey or casein!) may have for athletes and gymrats.
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You want to know what kind of advantages this may be? Well, here is a brief overview of the latest scientific evidence that is either directly or indirectly related to potential beneficial effects of milk:
  • Consumption of 500 ml of milk post-exercise-induced muscle damage can limit decrements in muscle function in females, and limit increases in soreness and serum markers of muscle damage in females and males.

    That's not something I say, but something, scientists from the Institute of Technology in Carlow, Ireland, conclude based on their observations in 32 team sport players (male n = 16; female n = 16) who were randomly, but equally divided into four groups: male milk, male carbohydrate, female milk, and female carbohydrate. Immediately following muscle damaging exercise, participants consumed either 500 ml of milk or 500 ml of an energy-matched carbohydrate solution. Skeletal troponin I (sTnI), creatine kinase (CK), peak torque, counter movement jump height, 20 m sprint performance and passive and active soreness were recorded prior to and 24, 48 and 72 h post-exercise-induced muscle damage (EIMD).
    Figure 1: Brief overview of the most important facts (Rankin. 2015).
    What the scientists found was that the women experienced likely to very likely beneficial effect on attenuating losses in peak torque at 60°/s from baseline to 24, 48 and 72 h, and a likely beneficial effect in minimizing decrements in sprint performance and soreness over 72 h. Furthermore, the milk consumption was unlikely to have a negative effect on serum markers of damage from baseline to 48 and 72 h.

    For males, on the other hand, milk had an unclear effect on muscle function variables. Milk had a most likely/likely beneficial effect on limiting muscle soreness from baseline to 72 h, and a possible beneficial effect on attenuating increases in CK. The effect on sTnI was unlikely to be negative from baseline-72 h. In that, the female participants demonstrated smaller increases in sprint time, passive soreness, active soreness (non-dominant leg) and sTnI values and did thus benefit to a greater yet not significantly greater extent from the 500 ml of milk - that's a difference that could be both sex- and/or protein-specific; I mean, for a man, 500 ml of milk yield significantly less protein on a per kg body weight basis than the same 500 ml do for a woman. That's a difference that could well partly explain why women benefit more from milk vs. carbohydrates only compared to men.
  • The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers.

    Obviously, working out will only help you shed body fat if the increased energy expenditure during the workout is not (over-)compensated by increased food intake after your workouts. Against that background the results from a recent study from the Northumbria University (Rumbold. 2015) are significant, because they indicate that 600 mL of skimmed milk have a significantly more pronounced "anti-binging" effect than 600 mL of an isocaloric orange drink when they are ingested immediately after a workout.
    Figure 2: Absolute and relative energy intake during the milk vs. orange juice trials (Rumbold. 2015).
    As the data in Figure 2 indicates the 9 female recreational exercisers (19.7 ± 1.3 years) who completed a standardized exercise regimen consisting of an VO2 peak test and 30 min of moderate-vigorous exercise (65% V̇O2peak) consumed 25.2% ± 16.6% less energy on an ad-libitum pasta meal that was served 60 minutes after the workout.

    If we assume that they women didn't compensate for the "missing" 25% of the energy later during the day and assuming that they did the workout 2x per week, the 169kcal per workout would yield a total fat loss of 1.9kg per 6 months - well, if the 7,000kcal deficit per 1kg of fat equation actually held ;-)
  • Milk-based drinks are more effective rehydration options compared with traditional sports drinks. The additional energy, protein, and sodium in a milk-based liquid meal supplement facilitate superior fluid recovery following exercise.

    The aim of a recent study from the Griffith University study was to compare the rehydration potential of a carbohydrate-electrolyte beverage with several varieties of milk following exercise-induced fluid losses. Fifteen male participants (age 24.9 ± 5.5 years, height 179.3 ± 4.9 cm, body mass 75.8 ± 6.6 kg (mean ± SD)) lost 2.0% ± 0.2% body mass through intermittent cycling before consuming a different beverage on 4 separate occasions.

    The drinks that were tested included cow's milk (286 kJ·100 mL(-1)), soy milk (273 kJ·100 mL(-1)), a milk-based liquid meal supplement (Sustagen Sport (Nestle); 417 kJ·100 mL(-1)), and a sports drink (Powerade (Coca Cola Ltd); 129 kJ·100 mL(-1)). Beverages were consumed over 1 h in volumes equivalent to 150% of body mass loss. Body mass, blood and urine samples, and measures of gastrointestinal tolerance were obtained before and hourly for 4 h after beverage consumption.
    Figure 3: Overview of the most important study results (Desbrow. 2014).
    The results show that the net body mass at the conclusion of each trial was significantly less with Powerade (-1.37 ± 0.3 kg) than with cow's milk (-0.92 ± 0.48 kg), soy milk (-0.78 ± 0.37 kg), and Sustagen Sport (-0.48 ± 0.39 kg). Net body mass was also significantly greater for Sustagen Sport compared with cow's milk trials, but not soy milk. Upon completion of trials, the percentage of beverage retained was Sustagen Sport 65.1% ± 14.7%, soy milk 46.9% ± 19.9%, cow's milk 40.0% ± 24.9%, and Powerade 16.6% ± 16.5%.

    If it were not for the fact that some of the subjects were complaining over increased bloating and fullnessduring all milk trials compared with Powerade, there would thus be no reason to go for the "classic" high carb + electrolyte solutions.
Are the hormonal side effects of dairy and its cancerous consequences even worse than they're painted by the steadily growing anti-dairy lobby? Find the answer to this and related questions in a previous SuppVersity article from January 2014 | read more.
Not all that glitters white like milk is gold, though. Only recently scientists from the Tokyo Metropolitan Institute of Gerontology had to realize that milk fat globule membranes, of which previous studies have shown that they may help avoiding metabolic syndrome (Pfeuffer. 2007), do not boost the already beneficial effects of exercise on the frailty status of elderly men and women (Kim. 2015).

Just like the previously discussed disappointing results of the Volterman (2014) study, the results Kim et al. present in their latest study do not negate the existing beneficial effects on satiety / anti-binging, muscle damage and function in response to muscle damaging exercise and rehydration discussed in this article | Comment on Facebook!
  • Desbrow, Ben, et al. "Comparing the rehydration potential of different milk-based drinks to a carbohydrate–electrolyte beverage." Applied Physiology, Nutrition, and Metabolism 39.12 (2014): 1366-1372.
  • Kim H, Suzuki T, Kim M, Kojima N, Ota N, Shimotoyodome A, Hase T, Hosoi E, Yoshida H. "Effects of Exercise and Milk Fat Globule Membrane (MFGM) Supplementation on Body Composition, Physical Function, and Hematological Parameters in Community-Dwelling Frail Japanese Women: A Randomized Double Blind, Placebo-Controlled, Follow-Up Trial." PLoS One 6;10.2 (2015):e0116256.
  • Pfeuffer, M., and J. Schrezenmeir. "Milk and the metabolic syndrome." Obesity reviews 8.2 (2007): 109-118.
  • Rankin P, Stevenson E, Cockburn E. "The effect of milk on the attenuation of exercise-induced muscle damage in males and females. Eur J Appl Physiol. (2015): Feb 12. [Epub ahead of print] 
  • Rumbold, Penny, et al. "Milk Consumption Following Exercise Reduces Subsequent Energy Intake in Female Recreational Exercisers." Nutrients 7.1 (2015): 293-305.
  • Volterman, Kimberly A., et al. "Effects of postexercise milk consumption on whole body protein balance in youth." Journal of Applied Physiology 117.10 (2014): 1165-1169.