Molecular adaptations of voltage‐gated sodium ion channel related proteins after fatiguing stretch‐shortening cycle exercise

Abstract

Dystrophin associated protein alpha-syntrophin is known to interact with voltage-gated sodium ion channel (NaCh). Dystrophin is known to be sensitive to eccentric muscle actions. For this reason, the function of the NaChs might also be affected. Molecular adaptations of dystrophin, alpha-syntrophin and NaChs were investigated after fatiguing stretch-shortening cycle (SSC) exercise, which consisted of unilateral jumps on a sledge apparatus. Muscle biopsies were taken from the vastus lateralis muscle of eight healthy subjects immediately after (IA) and 2 days after (2D) the exercise to analyze mRNA levels and immunohistochemical staining patterns. SSC exercise resulted in decreased isometric maximal voluntary contraction (IA: -31+/-9%, 2D: -14+/-16%) and a delayed increase of plasma creatine kinase activity (2D: +178+/-211%). Despite muscle soreness (P<0.001), no morphological damage was observed and no changes were found in the mRNA concentrations. However, the relative changes of the mRNA concentrations of alpha-syntrophin and NaChs were highly correlated (r=0.93, P<0.001) 2D after SSC exercise. This consistent pattern of mRNA regulation may imply a functional relationship between these two proteins. In addition, the current experiment emphasises high inter-individual variation in molecular responses to heavy exercise.

The Effects of Cold Water Immersion on the Recovery of Drop Jump Performance and Mechanics: A Pilot Study in Under-20 Soccer Players

“…Subjects performed less jumps compared to other maximally exhaustive SSC exercise investigations (Kuitunen et al, 2004;Piitulainen et al, 2008). In the present study, subjects ceased jumping upon volitional fatigue or if they could not maintain a rebound height of 50% of maximal, whereas subjects previously (Kuitunen et al, 2002(Kuitunen et al, , 2004Nicol et al, 2003;Dousset et al, 2007;Piitulainen et al, 2008) continued rebounding until they "were completely exhausted so that they were unable to jump off the force plate of the sledge" (Kuitunen et al, 2004). While such fully exhaustive protocols are recommended to reduce intersubject variability in fatigue (Nicol et al, 2006), they rarely occur in sporting environments and thus we deemed it not practically applicable to use such a protocol.…”

“…Exhaustive SSC exercise on a sledge apparatus has previously been shown to significantly increase muscle soreness that remains elevated for at least 48 h (Nicol et al, 2003;Piitulainen et al, 2008). Studies that have compared CON and CWI after SSC exercise have found that active muscle soreness is increased for both groups at both 24 and 48 h after single (Leeder et al, 2015;Vieira et al, 2016;Anderson et al, 2018;Ahokas et al, 2019) and multiple (Howatson et al, 2009) immersions.…”

“…After a 10 min standardized cycle ergometer warm-up (Regueme et al, 2005), subjects performed 100 successive maximal bilateral DJs from the optimal dropping height (Kuitunen et al, 2002(Kuitunen et al, , 2004Nicol et al, 2003;Dousset et al, 2007) divided into five sets of 20 with 2 min rest between sets (Miyama and Nosaka, 2004). This protocol has been shown to induce muscle damage (Kuitunen et al, 2002;Miyama and Nosaka, 2004;Dousset et al, 2007;Piitulainen et al, 2008) and has been used in other CWI recovery studies (Howatson et al, 2009;Vieira et al, 2016). Five seconds were given between each successive maximal DJ (signaled via an audible metronome).…”