Abstract
It was evaluated whether upper‐body compared to lower‐body musculature exhibits a different phenotype in relation to capacity for handling reactive oxygen species (ROS), H+, La−, Na+, K+ and also whether it differs in adaptive potential to exercise training. Eighty‐three sedentary premenopausal women aged 45 ± 6 years (mean ± SD) were randomized into a high‐intensity intermittent swimming group (HIS, n = 21), a moderate‐intensity swimming group (MOS, n = 21), a soccer group (SOC, n = 21), or a control group (CON, n = 20). Intervention groups completed three weekly training sessions for 15 weeks, and pre‐ and postintervention biopsies were obtained from deltoideus and vastus lateralis muscle. Before training, monocarboxylate transporter 4 (MCT4), Na+/K+ pump α 2, and superoxide dismutase 2 (SOD2) expressions were lower (P < 0.05) in m. deltoideus than in m. vastus lateralis, whereas deltoid had higher (P < 0.05) Na+/H+ exchanger 1 (NHE1) expression. As a result of training, Na+/K+ pump α 2 isoform expression was elevated only in deltoideus muscle, while upregulation (P < 0.05) of the α 1 and β 1 subunits, phospholemman (FXYD1), NHE1, and superoxide dismutase 1 expression occurred exclusively in vastus lateralis muscle. The increased (P < 0.05) expression of MCT4 and SOD2 in deltoid muscle after HIS and vastus lateralis muscle after SOC were similar. In conclusion, arm musculature displays lower basal ROS, La−, K+ handling capability but higher Na+‐dependent H+ extrusion capacity than leg musculature. Training‐induced changes in the ion‐transporting and antioxidant proteins clearly differed between muscle groups.
Highlights
The majority of research focusing on human skeletal muscle adaptation to exercise training investigates only m. vastus lateralis, and the fact that leg musculature may not be representative of all muscle groups is often disregarded
We have previously demonstrated that resting muscle glycogen concentration increased in m. deltoideus following a period of high-intensity interval swimming training, whereas it was unaffected by soccer training in m. vastus lateralis (Nordsborg et al 2015)
The primary findings of the present study were that basal expression of monocarboxylate transporter 4 (MCT4), Na+/K+ pump a2, superoxide dismutase 2 (SOD2), and glucose transporter 4 (GLUT4) were lower in arm than in leg musculature, whereas the expression of Na+/H+ exchanger 1 (NHE1) was higher
Summary
The majority of research focusing on human skeletal muscle adaptation to exercise training investigates only m. vastus lateralis, and the fact that leg musculature may not be representative of all muscle groups is often disregarded. Vastus lateralis, and the fact that leg musculature may not be representative of all muscle groups is often disregarded. Upper-body musculature has higher anaerobic a 2017 The Authors. Arm and Leg Muscle Adaptive Response energy production than lower-body muscles. Vastus lateralis, despite similar fiber type distribution (Kiilerich et al 2008), which suggests that lactate production and oxidation is higher and lower, respectively, in arm than in leg musculature (Jacobs et al 2013). It appears likely that the higher reliance on anaerobic metabolism in upper-body musculature is associated with a higher capacity for acid/base regulation, including a higher expression of the lactate/H+ cotransporter monocarboxylate transporter 4 (MCT4) as well as the Na+/H+ exchanger 1 (NHE1) as compared to lower-body musculature, but this is yet to be examined
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