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This study aimed to elucidate whether muscle blood flow restriction during maximal exercise is associated with alterations in hemodynamics, cerebral oxygenation, cerebral activation, and deterioration of exercise performance in male participants. Thirteen healthy males, cyclists (age 33 ± 2 yrs., body mass: 78.6 ± 2.5 kg, and body mass index: 25.57 ± 0.91 kg·m−1), performed a maximal incremental exercise test on a bicycle ergometer in two experimental conditions: (a) with muscle blood flow restriction through the application of thigh cuffs inflated at 120 mmHg (with cuffs, WC) and (b) without restriction (no cuffs, NC). Exercise performance significantly deteriorated with muscle blood flow restriction, as evidenced by the reductions in V˙O2max (−17 ± 2%, p < 0.001), peak power output (−28 ± 2%, p < 0.001), and time to exhaustion (−28 ± 2%, p < 0.001). Muscle oxygenated hemoglobin (Δ[O2Hb]) during exercise declined more in the NC condition (p < 0.01); however, at exhaustion, the magnitude of muscle oxygenation and muscle deoxygenation were similar between conditions (p > 0.05). At maximal effort, lower cerebral deoxygenated hemoglobin (Δ[HHb]) and cerebral total hemoglobin (Δ[THb]) were observed in WC (p < 0.001), accompanied by a lower cardiac output, heart rate, and stroke volume vs. the NC condition (p < 0.01), whereas systolic blood pressure, rating of perceived exertion, and cerebral activation (as assessed by electroencephalography (EEG) activity) were similar (p > 0.05) between conditions at task failure, despite marked differences in exercise duration, maximal aerobic power output, and V˙O2max. In conclusion, in trained cyclists, muscle blood flow restriction during an incremental cycling exercise test significantly limited exercise performance. Exercise intolerance with muscle blood flow restriction was mainly associated with attenuated cardiac responses, despite cerebral activation reaching similar maximal levels as without muscle blood flow restriction.

Dietary protein with adequate essential amino acids effectively stimulates protein synthesis and improves muscle mass. Musculoskeletal disorders in lower or upper limbs are not uncommon among patients with type II diabetes mellitus (T2DM). Therefore, this study primarily examines the effects of chronic dietary protein manipulation on amino acids’ profile and position sense in the elderly suffering from T2DM. A total of 26 individuals suffering from non-insulin-dependent T2DM (age > 55 years old) participated in a 12 week nutritional intervention. The subjects were randomly assigned and the control group received 0.8–1.0 g protein/kg/day, while the intervention group received 1.2–1.5 g protein/kg/day. Lean body mass, muscle strength, and position sense were assessed at baseline, as well as at the 6th and 12th week of the intervention. Only in the intervention group, the essential amino acids intake met the current nutritional recommendations (p < 0.05), while, by the 12th week, only the intervention group showed significant improvement in the muscle strength of knee (p < 0.05) and shoulder (p < 0.05) extension. On the contrary, in the control group, a significant decline in appendicular lean mass (p < 0.05) was observed by the 12th week. Position sense at the knee joint revealed a tendency for improvement in the intervention group by the 12th week (main effect of time p = 0.072). In the present investigation, it was revealed that the higher protein intake in the intervention group seemed to have positive effects on muscle strength and nearly positive effects on position sense.

Background: Type 2 diabetes mellitus (T2DM) is linked to accelerated losses in muscle function. The aim of the present investigation was to evaluate the effect of chronic higher-protein intake on isokinetic knee performance in the older adults with type 2 diabetes mellitus (T2DM). Methods: Thirty adults (15 men and 15 women) aged 60–80 years with non-insulin-treated T2DM and sarcopenia-related deficits were randomized for 12 weeks to a higher-protein diet (1.2–1.5 g·kg−1·day−1) or a recommended protein diet (0.8–1.0 g·kg−1·day−1), with meal plans designed to maintain body mass. Protein was increased mainly through Mediterranean-style protein sources while diet was monitored using repeated 3-day recalls. Isokinetic knee extensors and flexors peak torque (angular velocity 60°/s) was assessed at baseline and at week 6 and at the end of the 12th week of intervention. Fatigability (20 maximal contractions at an angular velocity at 180°/s) and DXA body composition were assessed at baseline and at the end of the 12th week of intervention. Data were analyzed using two-way repeated-measures ANOVA with repeated measures on time (2 groups × 3 time points), followed by post hoc analysis when significant difference was occurred. Results: Thirty participants completed the trial. Energy intake and body mass remained stable in both groups. At the end of week 12, peak torque declined in the control group (p < 0.05) but remained stable in the higher-protein group. The fatigue index worsened over time in controls but was preserved in the higher protein group, resulting in a significant group d7 time interaction at week 12 (p < 0.05) (post hoc between-group difference at week 12, p < 0.05). Fat-free mass and blood pressure did not change. In fat mass, a decrease was observed with higher protein intake, whereas it remained stable in the control group. Conclusions: Higher protein intake for 12 weeks preserved knee muscle performance in older adults with T2DM without weight gain, supporting dietary protein optimization to counter functional decline.

We examined the effects of carbohydrate ingestion on endurance performance and fatigue during a soccer simulation in adolescent soccer players and evaluated the protocol’s reliability. Nine (13.5 ± 0.4 years pre-PHV) soccer players performed two soccer simulation intermittent exercise sessions on the treadmill (60 min) while consuming 4 boluses of either a CHO or PLC beverage in random, counterbalanced order. Before and immediately after each exercise session, MVC was measured for the quadriceps and the hand. Participants also performed a TTE on a cycle ergometer on three occasions, after each simulation exercise session (CHO and PLC), and on another day in a rested state (CON). The simulation protocol produced an ICC of 0.96 ([0.77–0.98 95%CI], p = 0.01) for VO2, with 2.24%CV between trials, suggesting strong reliability. TTE was higher (p = 0.01) in the CHO condition (123 ± 33 s) compared to PLC (85 ± 5 s) by 29%. The relative reduction in MVCLEG was more pronounced in the PLC (22 ± 11%) condition than in CHO (14 ± 6%) (p = 0.05). Compared to the PLC, CHO resulted in lower RPElocal during the second half of the simulation protocol (p < 0.05). Carbohydrate ingestion can improve endurance performance and reduce peripheral fatigue during a reliable soccer simulation that resembles the physiological demands of a youth soccer match.

Purpose This study examined the physiological responses of ten elite divers to normal breathing (BHn), glossopharyngeal inhalation (BHi), and complete exhalation (BHe) prior to five maximal breath-hold (BH) efforts. Methods Breath-hold time (BHT), hemological variables, mean arterial pressure (MAP), other hemodynamic indices, and diaphragmatic activity (DA) were recorded. During BHs, phases were identified as easy-going (EPh: minimal DA), struggling (SPh: increased DA), PhI (MAP transition), PhII (MAP stabilization), and PhIII (steep MAP increase). Results BHi significantly extended BHT (309.14 ± 12.91 s) compared to BHn (288.77 ± 10.99 s) and BHe (151.18 ± 10.94 s) ( P  = 0.001). BHT, EPh, and SPh in BHi increased by 7.05%, 2.57%, and 11.08% over BHn, respectively. PhIII appeared earlier in BHe than in other conditions ( P  < 0.001) and accounted for 47.07%, 44.96%, and 60.18% of BHT in BHn, BHi, and BHe, respectively. SPh comprised 47.10%, 46.01%, and 45.13% of BHT in BHn, BHi, and BHe, respectively, with SPh onset coinciding with PhIII onset in BHn and BHi but not in BHe. Bradycardia was more pronounced in BHe, maintaining better stroke volume. No significant differences in red blood cells or maximal MAP were noted across conditions. Conclusion Glossopharyngeal inhalation improves BHT and extends EPh and SPh durations. PhIII onset is linked to SPh in BHn and BHi but not in BHe. BHe triggers an earlier MAP rise, leading to stronger parasympathetic responses. Despite similar maximal MAP across conditions, the higher BHT and tissue hypoxemia in BHi and BHn suggest MAP is a key limiting factor in apnoea. Graphical abstract

Despite its comparatively limited size in humans, spleen has been shown able to expel red-blood cells in the circulation and thus augment blood oxygen-carrying capacity under certain physiologic conditions. In the present state-of-the-art review, the short- and long-term regulation of spleen volume will be discussed. With regards to the physiological mechanism underlying spleen contraction, sympathetic activation stands as the prime contributor to the response. A dose-dependent relationship between specific interventions of apnea, exercise and hypoxia (imposed separately or in combination) and spleen contraction alleges to the trainability of the spleen organ. The trainability of the spleen is further substantiated by virtue of cross-sectional and longitudinal studies reporting robust increases in both organ volume at rest and subsequent spleen contraction. Alternative ways to assess the relationship between hematologic gains and the magnitude of spleen contraction (i.e., the reduction of spleen volume) will be presented herein. In extension of changes in the conventional measures of hemoglobin concentration and hematocrit, assessment of hemoglobin mass and total blood volume using the (safe, low-cost and time-efficient) CO-rebreathing technique could deepen scientific knowledge on the efficiency of human spleen contraction.

Thermoregulatory and cardiovascular responses during cycling in temperate and warm environments without and with application of capsaicin on the skin were investigated. We hypothesized that regardless of environmental temperature, capsaicin application would activate heat loss mechanisms attenuating exercise‐induced rectal temperature (Tre) and blood pressure increase. Eight males cycled at 55% of their maximal aerobic power so long as to reach 38.2°C Tre at 20.8 ± 1.0°C and at 30.6 ± 1.1°C ambient temperatures twice: without (NCA) and with (CA) application of capsaicin patches (12 × 18 cm, 4.8 mg). Patches were applied on pectoralis major, trapezius and vastus lateralis muscles. Thermoregulatory (Tre, proximal‐distal skin temperature gradient, sweating rate), cardiovascular variables and oxygen uptake were continuously recorded. In both ambient conditions, during the first 14 min of exercise, the local vasoconstrictive tone as a function of the relative change in Tre was lower in CA than NCA (p < .05, d = 0.84–1.15). Further, sweating rate was higher and occurred at a lower Tre increase in CA compared to NCA (p = .03, d = 0.6) resulting in extended time to reach 38.2°C Tre (p = .03, d = 0.9). Moreover, oxygen consumption was higher in CA than in NCA (p < .001, d = 0.8). Mean arterial pressure was lower during cycling in warm compared to temperate environment, but was unaffected by capsaicin. We conclude that activation of thermal sensors by capsaicin results in lower Tre rise during exercise, which is mediated through greater skin vasodilation along with higher rate and earlier onset of sweating. Nonetheless, capsaicin application has no extra effect on exercise cardiovascular responses. Capsaicin application on the human skin right before the initiation of cycling induced vasodilation and a higher rate and earlier onset of sweating resulting to a lower rectal temperature increase during exercise. These effects were unaffected by ambient temperature (temperate or warm). Capsaicin application had no extra effect on cardiovascular responses.

The aim of the present study was to study the effects of cycling and pure concentric and pure eccentric high-intensity interval exercise (HIIE) on skeletal muscle (i.e., vastus lateralis) and cerebral oxygenation. Twelve healthy males (n = 12, age 26 ± 1 yr, body mass 78 ± 2 kg, height 176 ± 2 cm, body fat 17 ± 1% of body mass) performed, in a random order, cycling exercise and isokinetic concentric and eccentric exercise. The isokinetic exercises were performed on each randomly selected leg. The muscle and the cerebral oxygenation were assessed by measuring oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation index. During the cycling exercise, participants performed seven sets of seven seconds maximal intensity using a load equal to 7.5% of their body mass while, during isokinetic concentric and eccentric exercise, they were performed seven sets of five maximal muscle contractions. In all conditions, a 15 s rest was adopted between sets. The cycling HIIE caused greater fatigue (i.e., greater decline in fatigue index) compared to pure concentric and pure eccentric isokinetic exercise. Muscle oxygenation was significantly reduced during HIIE in the three exercise modes, with no difference between them. Cerebral oxygenation was affected only marginally during cycling exercise, while no difference was observed between conditions. It is concluded that a greater volume of either concentric or eccentric isokinetic maximal intensity exercise is needed to cause exhaustion which, in turn, may cause greater alterations in skeletal muscle and cerebral oxygenation.

Carbohydrate (CHO) supplementation during prolonged exercise postpones fatigue. However, the optimum administration timing, dosage, type of CHO intake, and possible interaction of the ergogenic effect with athletes’ cardiorespiratory fitness (CRF) are not clear. Ninety-six studies (from relevant databases based on predefined eligibility criteria) were selected for meta-analysis to investigate the acute effect of ≤20% CHO solutions on prolonged exercise performance. The between-subject standardized mean difference [SMD = ([mean post-value treatment group–mean post-value control group]/pooled variance)] was assessed. Overall, SMD [95% CI] of 0.43 [0.35, 0.51] was significant (p < 0.001). Subgroup analysis showed that SMD was reduced as the subjects’ CRF level increased, with a 6–8% CHO solution composed of GL:FRU improving performance (exercise: 1–4 h); administration during the event led to a superior performance compared to administration before the exercise, with a 6–8% single-source CHO solution increasing performance in intermittent and ‘stop and start’ sports and an ~6% CHO solution appearing beneficial for 45–60 min exercises, but there were no significant differences between subjects’ gender and age groups, varied CHO concentrations, doses, or types in the effect measurement. The evidence found was sound enough to support the hypothesis that CHO solutions, when ingested during endurance exercise, have ergogenic action and a possible crossover interaction with the subject’s CRF.

Purpose Protein supplementation has been proposed as an effective dietary strategy for maintaining or increasing skeletal muscle mass and improving physical performance in middle-aged and older adults. Diabetes mellitus exacerbates muscle mass loss, leading to many older adults with type 2 diabetes mellitus (T2DM) experiencing sarcopenia, and vice versa. Our objective was to assess the impact of increased dietary protein intake on muscle mass, strength, physical performance, and the progression of T2DM in middle-aged and older adults diagnosed with this condition. Methods A 12-week randomized, controlled, parallel pilot study was conducted with 26 patients diagnosed with T2DM and had either low muscle mass, or low muscle strength or poor physical performance (age > 55 years old), aiming to investigate the effects of a protein-rich diet in sarcopenic and metabolic markers. The control group received 0.8–1.0 g/kg/day, while the intervention group received 1.2–1.5 g/kg/day of protein respectively. Body composition, muscle mass/strength and biochemical parameters were measured before and after the intervention period. Results Different kinetics of skeletal muscle index (SMI), appendicular lean mass (ALM), hand grip strength (HGS), gait speed (GS) and standing balance (SB) ( p  < 0.05) were observed between two groups. Specifically, the intervention group showed a significant improvement in HGS ( p  < 0.001) and physical performance (timed-up-and-go, p  < 0.001; GS, p  = 0.011; SB, p  = 0.022), while the control group had its ALM ( p  = 0.014), SMI ( p  = 0.011) and HGS ( p  = 0.011) significantly reduced. The kinetics of metabolic markers indices was similar for both groups. Conclusion Current recommendation for protein intake (0.8–1 g/kg/day) is certainly not enough to ameliorate the muscle mass loss in middle age and older adults’ individuals with T2DM. In contrast, protein intake of 1.2–1.5 g/kg/day seems to be a more appropriate recommendation to combat upcoming sarcopenia, nonetheless the progression of T2DM was not interrupted.