Skeletal muscle and performance adaptations to high-intensity training in elite male soccer players: speed endurance runs versus small-sided game training.

PURPOSE: To examine the skeletal muscle and performance responses across two different exercise training modalities which are highly applied in soccer training. METHODS: Using an RCT design, 39 well-trained male soccer players were randomized into either a speed endurance training (SET; n = 21) or a small-sided game group (SSG; n = 18). Over 4 weeks, thrice weekly, SET performed 6-10 × 30-s all-out runs with 3-min recovery, while SSG completed 2 × 7-9-min small-sided games with 2-min recovery. Muscle biopsies were obtained from m. vastus lateralis pre and post intervention and were subsequently analysed for metabolic enzyme activity and muscle protein expression. Moreover, the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) was performed. RESULTS: Muscle CS maximal activity increased (P < 0.05) by 18% in SET only, demonstrating larger (P < 0.05) improvement than SSG, while HAD activity increased (P < 0.05) by 24% in both groups. Na+-K+ ATPase α1 subunit protein expression increased (P < 0.05) in SET and SSG (19 and 37%, respectively), while MCT4 protein expression rose (P < 0.05) by 30 and 61% in SET and SSG, respectively. SOD2 protein expression increased (P < 0.05) by 28 and 37% in SET and SSG, respectively, while GLUT-4 protein expression increased (P < 0.05) by 40% in SSG only. Finally, SET displayed 39% greater improvement (P < 0.05) in Yo-Yo IR2 performance than SSG. CONCLUSION: Speed endurance training improved muscle oxidative capacity and exercise performance more pronouncedly than small-sided game training, but comparable responses were in muscle ion transporters and antioxidative capacity in well-trained male soccer players.

No Effect of ß-alanine on Muscle Function and Kayak Performance.

PURPOSE: If ß-alanine supplementation counteracts muscular fatigue development or improves athletic performance was investigated. METHODS: Elite kayak rowers (10 men and 7 women) were supplemented with either 80 mg·kg body mass·d of ß-alanine or placebo for 8 wk. Muscular fatigue development was investigated by applying a 2-min elbow flexor maximal voluntary contraction (MVC). EMG was recorded continuously, and voluntary activation was determined 30, 60, 90, and 115 s into the 2-min MVC. In addition, performance was evaluated as 1000-m and 5 × 250-m kayak ergometer rowing. RESULTS: Force reduction during the 2-min MVC was similar before and after supplementation with ß-alanine (30.9% ± 10.3% vs 36.0% ± 14.1%) and placebo (35.5% ± 7.7% vs 35.1% ± 8.0%). No time effect was apparent in voluntary activation during the 2-min MVC. In addition, there was no detectable effect of ß-alanine supplementation on 1000-m kayak ergometer performance (ß-alanine: 0.26% ± 0.02% vs placebo: -0.18% ± 0.02%) or accumulated 5 × 250-m time (ß-alanine: -1.0% ± 0.3% vs placebo: -1.0% ± 0.2%). In 5 × 250 m, mean power output was reduced to a similar extent from first to fifth interval before and after supplementation with ß-alanine (23% ± 11% vs 22% ± 10%) and placebo (26% ± 13% vs 20% ± 5%). CONCLUSIONS: Two-minute MVC characteristics are unaffected by ß-alanine supplementation in elite kayakers, and likewise, both a 1000-m kayak ergometer time trial lasting 4-5 min and a 5 × 250-m repeated sprint ability were unaltered by supplementation.

Muscle ion transporters and antioxidative proteins have different adaptive potential in arm than in leg skeletal muscle with exercise training.

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 α2, 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 α2 isoform expression was elevated only in deltoideus muscle, while upregulation (P < 0.05) of the α1 and ß1 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.