|No, the message of this article is not that protein shakes don't work. It is that your (hopefully) tasty 20g of serving of whey is not going to build slabs of extra muscle.|
For some of you, this is yet probably not the only surprise this article holds. The large-scale clinical trial by Reidy, et al. did after all also confirm that protein blends may yield slightly better results than everyone's beloved whey protein.
In their large-scale clinical trial (cf. Reidy 2016a,b), the scientists from Texas broadened the scope of their analysis of the effects of a 12-week resistance training program from mere changes in body composition to measures of individual and myofiber-specific cross-sectional area increases, satellite cell numbers and the extent to which the muscle domains multiplied by myonuclear addition (that's important for continuous gains).
|Figure 1: CONSORT (Consolidated Standards of Reporting Trials) diagram of study recruitment, enrollment, randomization follow-up, and analysis (from Reidy 2016b).|
|Figure 2: Schematic of the resistance exercise training protocol (Reidy. 2016b)|
"RET was performed at an intensity of 60-80% of 1-repetition maximum (1-RM) and consisted of 3-4 sets of 8-10 repetitions performed to technical failure during the last set for each exercise. In week 1, 3 sessions were conducted at 3 sets of 10 repetitions at 60% 1-RM. In weeks 1-8, 2 sessions per week were performed at an intensity of 70% 1-RM, where 3 sets of 10 repetitions were the last set was performed to momentary muscular failure. Each session consisted of whole body resistance exercise that lasted ~60-70 min. To reduce the risk of injury and overtraining, one additional training session per week was conducted at 3 sets of 10 repetitions at 60% 1RM with the goal of not reaching momentary muscular failure. These sessions took place immediately before and after the 1-RM training days. In weeks 9-12, 2 sessions per week were performed at an intensity of 80% 1-RM, where 4 sets of 8 repetitions were performed to momentary muscular failure. The 3rd session was performed at an intensity of 60% 1-RM as indicated earlier. Each session consisted of whole body resistance exercise that lasted ~70-90 min. Resistance exercises included flat and incline chest press; leg press, curl and extension; seated pull-downs and rows; calf raises; and abdominal exercises. Participants rested for 1-2 minutes between exercises and individuals sets. 1-RM was directly tested on the chest press, leg press and knee extension" (Reidy 2016b).Participants were allowed to maintain their recreational physical activity but instructed not to do any other strength training outside of the study. To allow for unforeseen life events, participants were given 13 weeks following the familiarization period to complete 36 exercise sessions. This allowed for 100% exercise compliance.
|Table 1: Summary of all protein supplement studies with a placebo group directly assessing muscle mass during RET in young adults (Reidy 2017).|
- a soy-dairy protein blend (PB, N=22) - 25% soy protein isolate, 25% whey protein isolate, and 50% sodium caseinate,2.00 g leucine from the three protein sources
- a whey protein isolate (WP, N=15) - 100% whey protein isolate, 2.31g leucine from whey
|Figure 3: While the scientists recorded sign. increases in muscle thickness in the subjects' vastus intermedius, these changes, however, were - within statistical margins - identical for all trials (Reidy 2016b).|
Nevertheless, there were no significant differences in either of the main research outcomes, i.e. the lean mass (DXA data), vastus lateralis myofiber-type-specific cross-sectional-area, satellite cell content and myonuclear addition, which were assessed pre and post-resistance training. A closer analysis of the data reveals:
Against that background, it will probably not surprise you that, again on a treatment basis (no pooling of the two protein groups), no differences were reported for the separately measured leg muscle hypertrophy and vastus lateralis myofiber-type-specific cross-sectional-area (P<0.05 | not shown in any figure) in the latest follow-up (Reidy 2017).
Only when the scientists pooled the results of the two protein groups, they found a non-significant and very modest effect of protein supplementation on the increase in MHC I satellite cell content, isokinetic torque and a slight expansion of a greater proportion of larger MHC II fibers over placebo after resistance exercise training - a "benefit" that is nothing like those you'd expect if you read the grandiose promises in the shiny advertisements of the supplement industry.
Table 2: Total energy and macronutrient intake during the study (from Reidy 2016b, which is the large clinical of which the study at hand is a subset)
- adding protein, in general, i.e. pooling the results from PB and WP to PRO, increased the statistical sign. of the lean mass benefit to p = 0.050 (no sign. difference to MPB, still),
- despite the previously hinted at advantage of the blend, significant inter-group differences for soy-blend vs. whey were not observed for any of the parameters
|Figure 4: Upon closer scrutiny, the lean mass data reveals a non-sign. advantage for the protein blend (Reidy 2016b).|
But what about the "more helps more" studies by Antonio et al.? I have to admit that I cannot fully explain why Jose Antonio and colleagues saw much more significant increases in muscle gains in their often-cited study. It could be that this is a methodological issue Reidy et al. address in their discussion of the results with the increases in total lean mass measured by DXA being sign. more pronounced than the actual changes in muscle cross-sectional area (compare box in the bottom line of this article), which were not measured in the 2014 study by Antonio et al. On the other hand, it is likewise possible that it's simply a question of the amount of protein that's supplemented. In the three-year-old study that was enough to bump the subject's protein intake to 4.4g/kg body weight. Anyway... Antonio's observations do not refute the conclusion that a single protein shake won't do the muscle-building magic you're promised on the labels of the bazillion of different protein products on the market.Similarly, no treatment effects, i.e. effects due to a certain protein powder, were detected for the albeit highly significant training-induced changes in myosin heavy chain I and II myofiber satellite cell content and myonuclei content (P<0.05).
|Figure 5: Change in the relative frequency of larger vastus lateralis MHC II myofibers. Protein blend (PB) or whey protein (WP) or maltodextrin placebo (MDP). Data are mean ± SEM. TRT, treatment (Reidy 2017).|
- Antonio, Jose, et al. "The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals." Journal of the International Society of Sports Nutrition 11.1 (2014): 19.
- Reidy, Paul T., et al. "Protein supplementation has minimal effects on muscle adaptations during resistance exercise training in young men: A double-blind randomized clinical trial." The Journal of nutrition 146.9 (2016a): 1660-1669.
- Reidy, Paul T., and Blake B. Rasmussen. "Role of ingested amino acids and protein in the promotion of resistance exercise–induced muscle protein anabolism." The Journal of nutrition (2016b): jn203208.
- Reidy, Paul T., et al. "Protein Supplementation Does Not Affect Myogenic Adaptations to Resistance Training." Medicine & Science in Sports & Exercise (2017).