Maximal strength training-induced increase in efferent neural drive is not reflected in relative protein expression of SERCA

Abstract

Introduction Maximal strength training (MST), performed with heavy loads (~ 90% of one repetition maximum; 1RM) and few repetitions, yields large improvements in efferent neural drive, skeletal muscle force production, and skeletal muscle efficiency. However, it is elusive whether neural adaptations following such high intensity strength training may be accompanied by alterations in energy-demanding muscular factors. Methods Sixteen healthy young males (24 ± 4 years) were randomized to MST 3 times per week for 8 weeks (n = 8), or a control group (CG; n = 8). Measurements included 1RM and rate of force development (RFD), and evoked potentials recordings (V-wave and H-reflex normalized to M-wave (M) in the soleus muscle) applied to assess efferent neural drive to maximally contracting skeletal muscle. Biopsies were obtained from vastus lateralis and analyzed by western blots and real-time PCR to investigate the relative protein expression and mRNA expression of Sarcoplasmic Reticulum Ca2+ ATPase (SERCA) 1 and SERCA2. Results Significant improvements in 1RM (17 ± 9%; p < 0.001) and early (0–100 ms), late (0–200 ms) and maximal RFD (31–53%; p < 0.01) were observed after MST, accompanied by increased maximal Vmax/Msup-ratio (9 ± 14%; p = 0.046), with no change in H-reflex to M-wave ratio. No changes were observed in the CG. No pre- to post-training differences were found in mRNA or protein expressions of SERCA1 and SERCA2 in either group. Conclusion MST increased efferent neural drive to maximally contracting skeletal muscle, causing improved force production. No change was observed in SERCA expression, indicating that responses to high intensity strength training may predominantly be governed by neural adaptations.

Aerobic high‐intensity interval training and maximal strength training in patients with unspecific musculoskeletal disorders improve V̇O2peak and maximal strength more than moderate training

“…To the best of our knowledge, this is the first study to apply MST, that is, ∼90% 1RM, in this population, demonstrating an additional effect of ∼90% compared to ∼75% of 1RM in patients with unspecific MSDs. MST with emphasis on maximal intended velocity in the concentric phase is designed to target the nervous system in particular, and effectively improves maximal strength, rate of force development, and efferent neural drive (Fimland et al., 2010; Tøien et al., 2021; Unhjem et al., 2021).…”

In vitro mitochondrial and myogenic gene expression is influenced by formoterol in human myotubes

“…Recent evidence suggests peripheral effects of thyroid hormone signaling within SKM are substantial and play crucial roles in metabolism, function, and growth (Stefano et al 2021). For example, within SKM, intracellular calcium is managed by SERCA1/2 which, in turn, is upregulated by T3 and exercise (Tøien et al 2021). Analyzing the expression of THRα and the deiodinases DIO2 and DIO3 is of particular interest in helping to characterize SKM homeostasis due to their regulatory roles in mitochondrial biogenesis and myogenesis (Bloise et al 2018).…”

Maximal intended velocity enhances strength training-induced neuromuscular stimulation in older adults

“…Thus, by including MIV in strength training for older adults, which appears to primarily target motor unit discharge rate, it is likely that functional improvements will occur. In fact, previous chronic training studies, where MIV has been utilized in conjunction with high intensity (≥ 80% of 1RM), both early phase RFD and efferent neural drive has improved in both young (Tøien et al 2018a(Tøien et al , 2021 and older adults (Tøien et al 2018b;Unhjem et al 2015Unhjem et al , 2021. In contrast, when strength training is performed without an emphasis on MIV, improvements in early phase RFD are not always observed (Andersen et al 2010).…”