Friday, June 16, 2017

Will Partial Reps Give You Those Horseshoes Everyone Else But You Seems to Develop? 20% Increased Gains in 8 Wks

Partial reps for maximal increases in horseshoe (=triceps) size?
Believe it or not: A recent Japanese study suggests that "doing everything right" may be holding you back: doing triceps extensions over the full range of motion seems to be inferior to throwing around the weights over a partial range of motion - the effects may be mediated by temporary hypoxia, but before we delve into an analysis of the mechanisms and the practical relevance of the results, let's first take a look at what exactly Masahiro Goto and his colleagues did with their 44 resistance-trained male subjects (members of a resistance weight training club) before they arrived at the conclusion "that intramuscular hypoxia might facilitate muscular hypertrophy with PRE [partial reps] being more effective than FRE [full reps]" (Goto 2017).
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Goto et al. used a randomized, counterbalanced two-group (PRE and FRE) pre- and post-test design to investigate the effects on muscle strength and cross-sectional area (CSA). The subjects, all of whom had at least one year of resistance training experience, were divided into two groups, the...
  • PRE group (n = 22), in which the subjects performed the exercise over the limited elbow range from 45° to 90, and the ...
  • FRE group (n = 22), in which the subjects performed the exercise over the full elbow range from 0° to 120°, ...
... each performed only one (identical) exercise at their pre-determined 8-RM for 3 sets, with a minute interval between sets - the classic lying elbow extension (using a bench and a barbell | check it out) with different elbow joint range of motion. Intensity was increased by 2.5 kg on the first day of every week and adjusted to the maximum weight which can be performed 8 times per set (see Table 1).
Table 1: Changes in exercise intensity of 8RM during the 8-week exercise training (Goto 2017).
To compare the acute metabolic and mechanical responses to the PRE with FRE, area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and RMS of EMG were evaluated during and after PRE or FRE.  After assessing the acute effects, PRE or FRE were performed by each group three times a week for 8 weeks.
Figure 1: Oxygenation (left) and EMG activity (right); Means ± SD (n = 22 for both group) are shown. p < 0.05, significant differences between PRE and FRE values (*) and between before and after 8-week exercise training values (✣ | Goto '17)
All that to compare the long-term effects of PRE with FRE, CSA and muscular strength were evaluated - long-term effects of which you already know that the scientists ascribed them to one of the few statistically significant inter-group difference (lactate levels, not shown in Figure 1, were also slightly higher in the PRE vs. FRE group): the difference in muscle oxygenation (see Figure 1). What you've learned, yet, is that you the results include a highly significant difference in the increase in cross-sectional area of the triceps brachii (CSA) of the 44 young, male study subjects.
Figure 2: When it comes to the actual increase in triceps brachii "size", i.e. the cross-sectional area of the horseshoe-muscle, the authors observed a highly significant difference in favor of the partial rep group (Goto 2017).
With a >20% difference between the 48.7 ± 14.5% the subjects in the PRE group gained and the comparatively small 28.2 ± 10.9% in the FRE group, this difference wasn't just statistically significant, it was - at least that's what I guess - also significantly more pronounced than most of you probably expected the partial rep advantage to be (if you even believed that it may exist).
Full Squat for Full Size Gains, Partial Squat for Full Strength - For lower body, weight-bearing muscle different rules apply | learn more!
Do not falsely assume that the study at hand would prove a general superiority of partial over full reps As the authors point out, we have to assume "that weight-bearing and non-weight-bearing muscles react differently to a particular exercise" (Goto 2016), which may limit the significance of the results of the study at hand to upper extremity muscles. And in fact, as a SuppVersity reader you will remember that squats, i.e. an exercise for the legs and thus a weight bearing muscle group produce the greatest gains in size, when they're done over the full range of motion - and that despite the fact that partials produce identical, if not more pronounced strength gains.
This result does, as Goto et al. point out in the practical implications section of their paper, indicate that using an 8RM load and doing only the middle range of motion during triceps extensions will yield significantly greater size gains (in terms of muscle cross-sectional are) than doing the same exercise over the full range of motion.
Figure 3: The scientists found a significant correlation between the hypoxic effects of the training and the increase in muscle CSA only in the partial rep (PRE), yet not the full rep (FRE) group (Goto 2017)
What will probably intrigue you most, though, is that this form of training could turn out to be particularly useful for those of you who have been training for years, now, because it appears to restore the hypoxic muscle stimulation that's reduced over years of training and increased in response to the (a) higher muscular tension and (b) constant muscle contraction doing triceps extensions only over the partial rep range provides by leading to mechanical capillary compression and thus, consequently, a sign. restriction of blood flow to muscles. With the latter inducing a temporary state of intramuscular hypoxia that appears to blunted in trained athletes (Okamoto 2009), the PRE-advantage observed in the study at hand could/should remind you of the previously discussed advantages of blood flow restriction (BFR).
Bigger Triceps in 8 Weeks of Reduced Oxygen Training  | learn more
So, partial reps it is, right? For the triceps, the answer to this question does indeed seem to be "YES!" Or rather: "Yes, if we're talking about training the non-weight-bearing triceps muscle and, possibly, other upper body muscles." In that, the increased hypoxic stress and the correspondingly increased growth stimulus makes partial reps particularly interesting for trained individuals, for whom it becomes increasingly difficult to provide their body with adequate, novel growth-stimuli without risking to out-train their recovery capacity (overtraining) in their effort to make consistent, measurable and visible gains in both, muscle strength and size.

In view of the fact that using partial reps and thus reversing/compensating the previously alluded to training-induced decrease in exercise-induced temporal muscle hypoxia in was a novel stimulus for the trained participants of the study at hand, future RCTs will have to investigate whether the benefits are a mere result of a slowly but progressively waning novelty effect and will thus be lost after a couple of months of training with partial reps. In addition, it would be nice to investigate the exact difference in volume and total load lifted and its effects on your gains (this was not done in the study at hand). After all, it is quite obvious that the partial rep group will have been able to use higher loads - with a lower range of motion they may eventually have achieved the same volume, but still trained with significantly higher and thus more anabolic loads | Comment on Facebook!
References:
  • Goto, Masahiro, et al. "Partial range of motion exercise is effective for facilitating muscle hypertrophy and function via sustained intramuscular hypoxia in young trained men." The Journal of Strength & Conditioning Research (2017).
  • Okamoto, Takanobu, Mitsuhiko Masuhara, and Komei Ikuta. "Upper but not lower limb resistance training increases arterial stiffness in humans." European journal of applied physiology 107.2 (2009): 127-134.