Monday, June 15, 2015

Cramp Yourself to Bigger Calves: 9% Size Gain in 6 Weeks With 12 Sessions of Electrically Induced Muscle Cramps

NEMS ➾ Leg raises no more?
Yes, it sounds painful; and yes, it sounds awkward, but if you are having problems growing your calves, you may still be interested to hear what scientists from the Institute of Training Science and Sport Informatics at the German Sport University Cologne did to grow the calves of fifteen male sport students between the ages of 20 and 35 years volunteered to participate in their study (Behringer. 2015).

I mean, a 9% increased muscle in 6 weeks in subjects who train regularly (some of them play soccer which happens to be a nice calf builder, too) - that's interesting, isn't it?
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When the subjects had been randomly assigned to either one of the two treatment or the control group, the calf muscles of both legs were stimulated by the means of neuromuscular electrical stimulation (NMES), in an alternating fashion. A coin was tossed to determine which leg was assigned to the
  • CP, where the stimulation was strong enough to trigger cramping or 
  • nCP, where the muscle was stimulated, but not hard enough to cramp.
Consequently, four subjects underwent the CP in the dominant leg, while in six subjects the CP was applied to the non-dominant leg. The control group did not undergo any NMES or other intervention.
"The applied stimulation protocol consisted of two stimulation sessions per week. During the calf muscle stimulation, subjects were seated on an elevated platform with hip and knee joints flexed at ~90° and both legs hanging down freely. Following a warm-up, consisting of three sets of five voluntary calf raises, calf muscles (Mm. gastrocnemii) of both legs were stimulated alternately using a portable battery-powered stimulator (Compex 3, Compex, Ecublens, Switzerland). The stimulation protocol comprised three sets of biphasic rectangular-wave pulsed currents at 30 Hz above the individual cramp threshold frequency (CTF; see measurements), an impulse width of 150 μs per leg. The 30 Hz was added to the CTF as it has been previously reported that cramps do not occur soon after a first cramp episode, which may be a function of cramp induced CTF increments. [...] According to the literature and pre-studies from our work group (unpublished), cramps are induced almost solely in shortened muscles (Bertolasi. 1993). Therefore, a custom-built ankle brace that fixates the foot in a neutral position (0° plantarflexion) was used to avoid the development of muscle cramps within the nCP. By contrast, plantar flexion was unhindered in the CP to elicit EIMCs" (Behringer. 2015).
Each set consisted of 6 x 5 s contractions, intermitted by a 10 s break - resulting in a duty cycle of 0.33. Each set was followed by a 90 s pause. During this pause, the opposing leg was stimulated using the same stimulation protocol. Electrical stimulation was delivered to the medial (MG) and lateral (LG) head of the m. gastrocnemius.
You do know that...? (a) you are not going to see gains if you cramp for other reasons; (b) these other reasons can be mineral deficiencies, but magnesium is actually very rarely the culprit (sodium and calcium deficiencies are more likely to cause cramping especially in people who exercise); (c) having the occasional cramp is normal, but frequent cramping can be a sign for several diseases like liver failure, diabetes, etc - if you are cramping frequently, talk to your doctor and try to find out what it is that makes you so susceptible to cramps.
And the results were impressive - in both the NEMS w/out cramping (nCP) and the NEMS with cramping (CP) groups, the scientist observed significant increases in muscle size (Figure 1).
Figure 1: Changes in maximal voluntary contractile force at 0% and 30% plantar flexion and muscle cross-sectional are (mCSA) in subjects in the cramping (CP), non-cramping (nCP) and control (CG) groups (Berlinger. 2015).
What is strange, though, is the fact that these size-increases were accompanied by statistically significant increases of maximal contractile force only in the non-cramping group. In the cramping group there was only a visible "trend" for strength gains at 30%, but not 0% plantar flexion.
This is not the first time you read about NEMS and calf muscle training at the SuppVersity. A previous non-cramping study found similar increases in strength as the one at hand | go back
What do we make of the results? The fact that the strength gains in the cramping group didn't reach statistical significance is odd, but no conclusive prove that the ~10% strength increase is not relevant. With the small number of subjects in each arm of the study it's well possible that a larger-scale study would have found statistically significant strength increases in both groups, even though Behringer et al. apparently believe that the lack of strength increases was a logical consequence of the "well-known length specificity during isometric training (Kitai. 1989), which has been reported to be more pronounced at short muscle lengths (Thepaut-Mathieu. 1988)" (Berlinger. 2015).

What exactly it is that explains the difference is yet up to speculation until future studies elucidate the exact mechanism by which the NEMS induced cramps trigger calf muscle hypertrophy | Comment on Facebook!
  • Behringer, M., et al. "Electrically induced muscle cramps induce hypertrophy of calf muscles in healthy adults." Journal of musculoskeletal & neuronal interactions 15.2 (2015): 227-236.
  • Bertolasi, L., et al. "The influence of muscular lengthening on cramps." Annals of neurology 33.2 (1993): 176-180.
  • Kitai, T. A., and D. G. Sale. "Specificity of joint angle in isometric training." European journal of applied physiology and occupational physiology 58.7 (1989): 744-748.
  • Thepaut-Mathieu, C., J. Van Hoecke, and B. Maton. "Myoelectrical and mechanical changes linked to length specificity during isometric training." Journal of Applied Physiology 64.4 (1988): 1500-1505.