Futsal and continuous exercise induce similar changes in specific skeletal muscle signalling proteins.

Exercise elicits skeletal-muscle adaptations which are important for improved health outcomes. We compared the effects of a futsal game (FUT) and moderate-intensity continuous exercise (MOD), on the skeletal-muscle protein signalling responses in young, healthy individuals. 16 men undertook an incremental exercise test and a resting muscle biopsy performed >48 h apart. They were then randomly allocated to either FUT (n=12) consisting of 2 x 20 min halves, or MOD (n=8) consisting of a work-matched running bout performed at an intensity corresponding to the individual ventilatory threshold 1. Work matching was achieved by means of triaxial accelerometers. Immediately after FUT and MOD, participants underwent a second biopsy to assess exercise-induced changes in protein signalling. Total and phosphorylated protein abundance was assessed via western blotting. Both FUT and MOD altered signalling responses in skeletal muscle. FUT increased total ATF2 protein abundance (p=0.048) and phosphorylation (p=0.029), while no changes occurred with MOD. Both exercise regimes increased ACC phosphorylation (p=0.01) and returned a trend for increased p38MAPK phosphorylation. Futsal may be employed as an alternative to continuous exercise to elicit muscle adaptations which may be associated with improved health outcomes. As only FUT increased ATF2 activation, this protein might be a target of future investigation on exercise-induced signalling.

Uphill versus downhill high-intensity training effectiveness in preserving vascular function and exercise performance in runners who reduce their regular endurance training.

Purpose: The COVID-19 restrictions have limited outdoor physical activities. High-intensity training (HIT) may be a valid indoor alternative. We tested whether an indoor HIT is effective in maintaining vascular function and exercise performance in runners who reduce their usual endurance training, and whether a downhill HIT is as effective as an uphill one for such purposes. Methods: Sixteen runners performed the same 6-week HIT either uphill (UP, eight runners) or downhill (DOWN, eight runners). Eight runners continuing their usual endurance training acted as a control group (CON). The following data were collected before vs after our HIT: vascular conductance during rapid leg vasodilation to assess vasodilation capacity; V̇O2max through running incremental test to exhaustion; 2000 m running time; neuromuscular indexes related to lower-limb muscle strength. Results: Both uphill and downhill HIT failed in maintaining the pre-HIT leg vasodilation capacity compared to CON, which was, however, blunted more after uphill than downhill HIT. V̇O2max and 2000 m time were similar after downhill HIT compared to CON, and augmented after uphill HIT compared to CON and DOWN. Indexes of lower-limb muscle strength were similar before vs after HIT and among groups. Conclusion: Our HIT was ineffective in maintaining the pre-HIT leg vasodilation capacity compared to runners continuing their usual low-intensity endurance training, but did not lead to reductions in V̇O2max, 2000 m time performance, and indexes related to lower-limb muscle strength. Our data show an appealing potential for preserving exercise performance with low cardiorespiratory effort via downhill running.

Energy cost and efficiency of Venetian rowing on a traditional, flat hull boat (Bissa).

The total net metabolic power output (E, kW) required to scull a traditional, flat hull boat--the "Bissa", 9.02 m long and weighting about 500 kg including the crew-was assessed at different constant speeds (nu) ranging from 2.44 to 3.75 m s(-1). E increased with the speed: E = 0.417 x e (0.664v ); r (2) = 0.931. The amount of metabolic energy spent per unit distance (C, J m(-1)) to move the "Bissa", calculated by dividing E by the corresponding nu, was a linear function of nu: C = 0.369 nu -0.063; r (2) = 0.821. The hydrodynamic resistance met by the boat in the water--drag (D, N)--was estimated by analysing the decay of the reciprocal of nu as a function of time measured during several spontaneous deceleration tests carried out in still water and by knowing the total mass of the watercraft plus crew. D increased as a square function of speed: D = 12.76 v (2). This allowed us to calculate the drag efficiency (g(d)), as the ratio of D to C: g(d) increased from 8.9 to 13.7% in the range of the speeds tested. The "Bissa" turned out to be as economical as other flat hull, traditional watercrafts, such as the bigger Venetian gondola, and her g(d) was similar to that of other modern and traditional watercrafts.

In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans.

AIM: To parse out the impact of advanced ageing and disuse on skeletal muscle function, we utilized both in vivo and in vitro techniques to comprehensively assess upper- and lower-limb muscle contractile properties in 8 young (YG; 25 ± 6 years) and 8 oldest-old mobile (OM; 87 ± 5 years) and 8 immobile (OI; 88 ± 4 years) women. METHODS: In vivo, maximal voluntary contraction (MVC), electrically evoked resting twitch force (RT), and physiological cross-sectional area (PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies of the vastus lateralis and biceps brachii facilitated the in vitro assessment of single fibre-specific tension (Po). RESULTS: In vivo, compared to the young, both the OM and OI exhibited a more pronounced loss of MVC in the lower limb [OM (-60%) and OI (-75%)] than the upper limb (OM = -51%; OI = -47%). Taking into account the reduction in muscle PCSA (OM = -10%; OI = -18%), only evident in the lower limb, by calculating voluntary muscle-specific force, the lower limb of the OI (-40%) was more compromised than the OM (-13%). However, in vivo, RT in both upper and lower limbs (approx. 9.8 N m cm(-2) ) and Po (approx. 123 mN mm(-2) ), assessed in vitro, implies preserved intrinsic contractile function in all muscles of the oldest-old and were well correlated (r = 0.81). CONCLUSION: These findings suggest that in the oldest-old, neither advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function, as assessed in vitro. However, in vivo, muscle function is attenuated by age and exacerbated by disuse, implicating factors other than skeletal muscle, such as neuromuscular control, in this diminution of function.

Acute variation of biochemical markers of muscle damage following a 21-km, half-marathon run.

OBJECTIVE: Although there is information on biochemical markers of muscle and cardiac damage following strenuous exercise, little is known about the kinetics of these markers in athletes performing sub-maximal exercise. MATERIAL AND METHODS: Fifteen healthy, trained, Caucasian males took part in a 21-km run. Blood samples were collected before the run, immediately after (post), and 3 h, 6 h and 24 h thereafter. Biochemical markers of muscle and cardiac damage were evaluated on the Modular System, employing proprietary reagents. In no case did the concentration of troponin T increase by >0.03 ng/mL. The values of aspartate aminotransferase (AST), creatine kinase (CK), CK MB, lactate dehydrogenase (LDH) and myoglobin increased significantly immediately after the run and remained elevated 24 h thereafter. RESULTS: The number of subjects with values above the upper limit of the relative reference ranges did not vary throughout the study period for AST and LDH, while it increased significantly for CK, CK MB and myoglobin. The major variation over the pre-run value was recorded for myoglobin (3-fold increment), whereas AST and LDH increased 1.1 and 1.3-fold, respectively. CONCLUSIONS: The results suggest the hypothesis that sub-maximal exercise influences the concentration of several biomarkers of muscle damage for up to 24 h with no biochemical signs of myocardial damage.

Acute variation of estimated glomerular filtration rate following a half-marathon run.

The accurate estimation of glomerular filtration rate (GFR) is pivotal in sports medicine. However, there is controversial information on the acute influence of physical exercise on kidney function in healthy athletes. The estimated GFR (EGFR) was assessed by the recommended Modification of Diet in Renal Disease (MDRD) equation before a 21-km half-marathon, at the end, and 3, 6, 24 hrs thereafter on 17 trained, middle-aged males. Results were corrected for plasma volume changes. The mean EGFR at the baseline was 76 mL/min/1.73 m (2); it decreased at the end of the run (62 mL/min/1.73 m (2)) and for the following 3 hrs (68 mL/min/1.73 m (2)) and 6 hrs (70 mL/min/1.73 m (2)), though statistical significance was only achieved immediately after the run (mean decrease 16 %, p < 0.01). The frequency of athletes with EGFR below the normal threshold was higher than the baseline immediately after the race and for the following 6 hrs. Twenty-four hours after the run, the EGFR had returned to values similar and nonsignificantly different from those recorded at the baseline. These results attest that medium to high strains of running in healthy, middle-aged, trained individuals do not cause renal damage, but a limited and temporary decline in renal function.