Cold-water immersion after training sessions: effects on fiber type-specific adaptations in muscle K⁺transport proteins to sprint-interval training in men

Abstract

Effects of regular use of cold-water immersion (CWI) on fiber type-specific adaptations in muscle K transport proteins to intense training, along with their relationship to changes in mRNA levels after the first training session, were investigated in humans. Nineteen recreationally active men (24 ± 6 yr, 79.5 ± 10.8 kg, 44.6 ± 5.8 ml·kg·min) completed six weeks of sprint-interval cycling, either without (passive rest; CON) or with training sessions followed by CWI (15 min at 10°C; COLD). Muscle biopsies were obtained before and after training to determine abundance of Na, K-ATPase isoforms (α, β) and phospholemman (FXYD1) and after recovery treatments (+0 h and +3 h) on the first day of training to measure mRNA content. Training increased ( P < 0.05) the abundance of α and β in both fiber types and β in type-II fibers and decreased FXYD1 in type-I fibers, whereas α and α abundance was not altered by training ( P > 0.05). CWI after each session did not influence responses to training ( P > 0.05). However, α mRNA increased after the first session in COLD (+0 h, P < 0.05) but not in CON ( P > 0.05). In both conditions, α and β mRNA increased (+3 h; P < 0.05) and β mRNA decreased (+3 h; P < 0.05), whereas α, β, and FXYD1 mRNA remained unchanged ( P > 0.05) after the first session. In summary, Na,K-ATPase isoforms are differently regulated in type I and II muscle fibers by sprint-interval training in humans, which, for most isoforms, do not associate with changes in mRNA levels after the first training session. CWI neither impairs nor improves protein adaptations to intense training of importance for muscle K regulation. NEW & NOTEWORTHY Although cold-water immersion (CWI) after training and competition has become a routine for many athletes, limited published evidence exists regarding its impact on training adaptation. Here, we show that CWI can be performed regularly without impairing training-induced adaptations at the fiber-type level important for muscle K handling. Furthermore, sprint-interval training invoked fiber type-specific adaptations in K transport proteins, which may explain the dissociated responses of whole-muscle protein levels and K transport function to training previously reported.

Molecular stressors underlying exercise training‐induced improvements in K+ regulation during exercise and Na+,K+‐ATPase adaptation in human skeletal muscle

“…In one of our recent studies, 6 weeks of sprint‐interval training increased (210% to 330%) α 1 abundance in both type I and II fibres in the skeletal muscle of recreationally‐active men . In agreement, 4 weeks of sprint‐interval training resulted in an elevated (29%) α 1 abundance in whole‐muscle samples from similarly trained subjects .…”

“…In extension of these results, blood flow restriction has been shown to augment increases in oxidative damage to a single exercise session, as well as facilitate training‐induced improvements in Na + ‐K + ‐ATPase‐isoform protein abundance and K + regulation in human skeletal muscle . Adding to this point, rapid and marked perturbations in redox homeostasis effectively increase ROS levels, whereas a single bout of post‐exercise cold‐water immersion, which is likely to temporarily perturb muscle redox state, caused a selective increase in Na + ‐K + ‐ATPase α 2 isoform mRNA expression in skeletal muscle of recreationally‐active men …”

“…However, most of these reviews go >15 years back and thus lack essential novel inputs, specifically about how different types of exercise training (eg interval‐endurance, sprint‐interval and resistance training regimens), may affect K + regulation and its key determinants, including Na + ,K + ‐ATPase function, content, and isoform expression, in humans. In line with findings in animals, a number of recent discoveries point to a different regulation of Na + ,K + ‐ATPase function and expression by exercise training between different human skeletal muscle fibre types . However, the potential implications of this fibre type‐dependent regulation have been scarcely examined.…”

Cycling with blood flow restriction improves performance and muscle K+ regulation and alters the effect of anti‐oxidant infusion in humans

“…; Christiansen, ; Christiansen et al . ). Despite these observations, it remains unresolved how training‐induced improvements in muscle K + regulation are associated with the modulation of Na + ,K + ‐ATPase‐isoform content at the fibre‐type level in humans.…”

“…; Christiansen, ; Christiansen et al . ), this relationship should be studied at the fibre‐type level.…”