The decline in performance in the NFOR group could be related to the decrease in muscle oxidative capacity. We observed a trend in the Gm/Ga and leukocytosis that is similar to what has been sometimes observed in overtrained humans. This controlled training-overtraining animal model may be useful for seeking causative mechanisms of performance decline.

SUMMARYSome wild antelopes are fast sprinters and more resistant to fatigue than others. This study therefore investigated two wild antelope species to better understand their reported performance capability. Muscle samples collected post mortem from the vastus lateralis and longissimus lumborum of fallow deer (Dama dama) and springbok (Antidorcas marsupialis) were analysed for myosin heavy chain isoform content, citrate synthase, 3-hydroxyacyl CoA dehydrogenase, phosphofructokinase, lactate dehydrogenase and creatine kinase activities. Cross-sectional areas, fibre type and oxidative capacities of each fibre type were determined in the vastus lateralis only. The predominant fibre type in both muscle groups and species were type IIX (>50%), with springbok having more type IIX fibres than fallow deer (P<0.05). Overall cross-sectional area was not different between the two species. The metabolic pathway analyses showed high glycolytic and oxidative capacities for both species, but springbok had significantly higher CS activities than fallow deer. Large variation and overlap in oxidative capacities existed within and between the fibre types. Some type IIX fibres presented with oxidative capacities similar to those from type I and IIA fibres. The data suggest that springbok and fallow deer are able sprint at >90 and 46kmh -1 , respectively, partly from having large type IIX fibre contents and high glycolytic capacities. The high oxidative capacities also suggest that these animals may be able to withstand fatigue for long periods of time.

Exercise training is known to induce an increase in free radical production potentially leading to enhanced muscle injury. Vitamins C and E are well known antioxidants that may prevent muscle cell damage. The purpose of this study was to determine the effects of these supplemental antioxidant vitamins on markers of oxidative stress, muscle damage and performance of elite soccer players. Ten male young soccer players were divided into two groups. Supplementation group (n=5) received vitamins C and E supplementation daily during the pre-competitive season (S group), while the placebo group (PL group, n=5) received a pill containing maltodextrin. Both groups performed the same training load during the three-month pre-season training period. Erythrocyte antioxidant enzymes glutathione reductase, catalase and plasma carbonyl derivatives did not show any significant variation among the experimental groups. Similarly, fitness level markers did not differ among the experimental groups. However, S group demonstrated lower lipid peroxidation and muscle damage levels (p<0.05) compared to PL group at the final phase of pre-competitive season. In conclusion, our data demonstrated that vitamin C and E supplementation in soccer players may reduce lipid peroxidation and muscle damage during high intensity efforts, but did not enhance performance.

de Souza, HLR, Arriel, RA, Hohl, R, da Mota, GR, and Marocolo, M. Is ischemic preconditioning intervention occlusion-dependent to enhance resistance exercise performance? J Strength Cond Res 35(10): 2706–2712, 2021—Ischemic preconditioning is a rising technique with potential to improve performance. Currently, its effects are still controversial, and a placebo effect seems to have a role. In this sense, this study evaluated the effect of high-pressure (HP) and low-pressure (LP) cuffing on resistance exercise performance during repeated 5-day intervention. Twenty healthy trained men (24.0 ± 4.4 years; 80.1 ± 12.2 kg; and 176.9 ± 6.6 cm) performed a 1 repetition maximum (1RM) test before interventions. Maximal isometric force test, number of repetitions (75% 1RM), total workload (sets × reps × load), fatigue index (FI) ([set 1 − set 3]/set 1 × 100), and perceived scales were assessed during knee extension preceded by HP (3 × 5-minute unilateral leg occlusion at 50 mm Hg above systolic blood pressure), LP (3 × 5-minute unilateral leg occlusion at 20 mm Hg), or control ([CON] 30-minute resting). The main effect of cuff intervention was significant for total workload (F(1,16) = 4.2, p = 0.03) after adjusting for baseline (analysis of covariance). Adjusted means (confidence interval) and effect sizes (ES) indicate that HP (1778 kg [1,613–1944]; ES: 0.29) and LP (1761 kg [1,590–1932]; ES: 0.34) significantly increased total workload compared with CON (1,452 kg [1,262–1,643]; ES: 0.17). Finally, isometric force and FI were similar for all conditions (HP, LP, and CON) with no difference from baseline performance. In conclusion, the short-term (5-day) intervention of HP and LP cuffing increases the total workload. This effect in muscle endurance performance is nondependent of blood flow occlusion, since LP is not able to obstruct arterial blood flow. A likely motivational effect cannot be ruled out.