Martim Bottaro

This study aimed to describe the upper-body bilateral deficit (BD) in recreational climbers and to examine its relationship with specific performance. Fifteen recreational climbers (11 men, 4 women; 25–45 years; ≥3 years of experience) performed unilateral and bilateral maximal isometric handgrip strength test (HGT), and unilateral and bilateral maximal isometric strength test using a climbing-specific fingerboard test (CSFT). The fatigue resistance index test (FRI) and the endurance capacity test (ECT) were used as performance tests. Paired Student’s T-tests were used to compare bilateral deficit results between CSFT and HGT. Pearson’s correlation was used to assess relationships between these variables with the level at 5%. The results showed a significant (p < 0.05) bilateral deficit in the CSFT (−2.53 ± 4.49%) and the HGT (−2.05 ± 3.29%), with no difference between methods. A positive correlation was found between bilateral deficit in the CSFT and the ECT (r = 0.53; p = 0.044), while no correlation was observed with the FRI. Relative bilateral strength to body mass was strongly associated with ECT (r = 0.92; p < 0.001). Greater bilateral deficit was associated with endurance capacity in climbers. In addition, the CSFT demonstrated good predictive accuracy and may be considered a specific and reliable tool for assessing BD in climbers.

This study examined neural and mechanical responses at the onset of prolonged static stretching performed at different amplitudes, their progression during the stretching period, and alterations immediately after its completion. Thirteen healthy adults completed three randomized sessions: control (15‐min rest in neutral ankle angle), 15 min of submaximal stretching (ROM _max − 5°), and 15 min of supramaximal stretching (ROM _max + 5°). Spinal excitability ( H _max / M _max ), evoked contractile properties (PTT), voluntary strength (MVC), passive torque, and maximal range of motion (ROM _max ) were assessed at baseline (PRE), during stretching (T ₀₀ , T ₀₅ , T ₁₀ , and T ₁₅ ), and immediately after stretching (POST). Spinal excitability decreased at stretch onset but progressively increased during stretching (T ₀₀ –T ₁₅ , p < 0.05), with greater facilitation in supramaximal (soleus and gastrocnemius, p < 0.001) than submaximal conditions (soleus only, p < 0.001). These changes were transient, returning to baseline at POST ( p < 0.001). Passive torque increased during both stretching ( p < 0.05); however, in supramaximal, it declined after 5 min and stabilized until 15 min ( p = 0.001), while in submaximal, it declined only at 15 min ( p = 0.043). Both conditions reduced PTT ( p < 0.05), with slightly greater decreases in the supramaximal condition. MVC decreased similarly after both protocols ( p < 0.05). ROM _max improved in both ( p < 0.05), with slightly greater gains in the supramaximal condition. Static stretching amplitude modulates neuromechanical adaptations. Both supramaximal and submaximal protocols reduced voluntary strength but improved flexibility, with greater spinal excitability after the initial decrease and slightly larger ROM _max gains at supramaximal amplitude.

Purpose: The effectiveness of neuromuscular electrical stimulation hinges on the evoked torque level, which can be attained through either conventional (CONV) or wide-pulse high frequency (WPHF). However, the best electrode placement is still unclear. This study adopted a crossover design to compare the effects of WPHF applied to the tibial nerve trunk (N-WPHF) or muscle (M-WPHF) with CONV in healthy participants. Methods: A total of 30 participants (age: 22.4 [4.5]) were involved in 4 sessions. During each session, participants performed: 2 maximal voluntary contractions, 2 contractions at maximal evoked torque, and 2 contractions at submaximal evoked torque at 20% maximal voluntary contraction. Neuromuscular electrical stimulation intensity-evoked torque, efficiency, and discomfort were measured in maximal and submaximal conditions. Statistical analyses were conducted using a 1-way mixed-model analysis of variance with repeated measures. Results: N-WPHF and M-WPHF showed higher evoked torque than CONV (P = .002 and P = .036) and greater efficiency than CONV for maximal evoked torque (P = .006 and P = .002). N-WPHF induced higher efficiency than M-WPHF and CONV for submaximal evoked torque (P = .004). Higher discomfort was observed for both N-WPHF and M-WPHF for submaximal evoked torque compared with CONV (P = .003 and P < .001). Conclusion: Our results suggest that WPHF applied at either the nerve or muscle could be the best choice for the maximal condition, whereas nerve application is preferred for the submaximal condition.

Low-load conditioning activity with blood flow restriction has been addressed as an efficient method to enhance an individual’s performance during their main exercise activity. However, the optimal degree of blood flow restriction remains unclear. Therefore, this study investigated the acute effects of low-load conditioning activity with different degrees of blood flow restriction on muscle strength, power, and perceived exertion. Twenty recreationally trained men (20.9 ± 2.3 years) participated in a randomized crossover design including three conditions: control, low-load blood flow restriction at 50%, and 75% of total arterial occlusion pressure. Participants performed squats (three sets of ten reps) followed by isokinetic assessments of the knee flexor and extensor performance at 7 and 10-min post-exercise. The session rating of perceived exertion (SRPE) was recorded 30 min after each session. No significant effects were observed for condition, time, or their interaction on peak torque, total work, or average power (p < 0.05). However, SRPE was significantly higher in the 75% BFR condition compared to both the 50% BFR and control conditions (p < 0.05), with no difference between the 50% BFR and control. These findings suggest that low-load conditioning activity with blood flow restriction does not acutely enhance neuromuscular performance. However, a higher degree of restriction increases perceived exertion.

O objetivo deste estudo foi determinar valores de referência (média ± desvio padrão) da densidade mineral óssea (DMO) da coluna lombar (L2-L4) e da extremidade proximal do fêmur (colo, trocânter maior, triângulo de Ward e fêmur total) em universitários do sexo masculino. Foram medidas as densidades minerais ósseas (DMOs) de 117 homens (25 sedentários e 92 ativos) com idades entre 20 e 35 anos, utilizando o método da absorciometria radiológica por raios X de dupla energia (DXA). As DMOs obtidas (em g/cm²) para cada região foram: L2-L4 - 1,24 ± 0,16; colo do fêmur - 1,22 ± 0,17; triângulo de Ward - 1,13 ± 0,21; trocanter maior - 1,02 ± 0,16 e fêmur total - 1,21 ± 0,16. Comparando estas DMOs com os valores de referência do fabricante do DXA foram obtidos os respectivos escores T: 0,03 ± 1,30; 1,18 ± 1,32; 1,28 ± 1,62; 0,80 ± 1,43 e 0,90 ± 1,27. Houve diferença estatisticamente significativa (p<0,001) entre os escores T obtidos com base no DXA e aqueles obtidos com base na própria amostra, em todos as regiões do fêmur, mas não na coluna lombar (p=0,79). Ao comparar as DMOs e os escores T entre sedentários e ativos, houve diferença estatisticamente significativa entre os valores relacionados ao fêmur (p<0,01), mas não entre os relacionados à coluna lombar (p=0,05). Os dados sugerem que cada indivíduo deve ter sua DMO avaliada com base em sua própria população e que há também uma influência da atividade física sobre a DMO.

Determining how the quadriceps femoris musculotendinous unit functions, according to hip and knee joint angles, may help with clinical decisions when prescribing knee extension exercises. We aimed to determine the effect of hip and knee joint angles on structure and neuromuscular functioning of all constituents of the quadriceps femoris and patellar tendon properties. Twenty young males were evaluated in four positions: seated and supine in both 20° and 60° of knee flexion (SIT20, SIT60, SUP20, and SUP60). Peak knee extension torque was determined during maximal voluntary isometric contraction (MVIC). Ultrasound imaging was used at rest and during MVIC to characterize quadriceps femoris muscle and tendon aponeurosis complex stiffness. We found that peak torque and neuromuscular efficiency were higher for SUP60 and SIT60 compared to SUP20 and SIT20 position. We found higher fascicle length and lower pennation angle in positions with the knee flexed at 60°. The tendon aponeurosis complex stiffness, tendon force, stiffness, stress, and Young’s modulus seemed greater in more elongated positions (60°) than in shortened positions (20°). In conclusion, clinicians should consider positioning at 60° of knee flexion rather than 20°, regardless if seated or supine, during rehabilitation to load the musculotendinous unit enough to stimulate a cellular response.

Background: Low-frequency electrical stimulation (LFES) is an adjuvant method for heart failure (HF) patients with restrictions to start an exercise. However, the impact on molecular changes in circulating is unknown. We investigated the effects of 10 weeks of home-based LFES on plasma cytokines profile, redox biomarkers, metalloproteinases (MMPs) activity, and exercise performance in HF patients. Methods: Twenty-four HF patients (52.45 ± 9.15 years) with reduced ejection fraction (HFrEF) (EF < 40%), were randomly assigned to a home-based LFES or sham protocol. Plasma cytokines profile was assessed through interleukins, interferon-gamma, and tumor necrosis factor levels. Oxidative stress was evaluated through ferric reducing antioxidant power, thiobarbituric acid-reactive substances, and inducible nitric oxide synthase. The MMPs activity were analyzed by zymography. Cardiorespiratory capacity and muscle strength were evaluated by cardiopulmonary test and isokinetic. Results: LFES was able to increase the active-MMP2 activity post compared to pre-training (0.057 to 0.163, p = 0.0001), while it decreased the active-MMP9 (0.135 to 0.093, p = 0.02). However, it did not elicit changes in cytokines, redox biomarkers, or exercise performance (p > 0.05). Conclusion: LFES protocol is a promising intervention to modulate MMPs activity in HFrEF patients, although with limited functional effects. These preliminary responses may help the muscle to adapt to future mechanical demands dynamically.

Aging is associated with neurodegeneration and a loss of muscle function, especially in lower-limb muscles. While caffeine may augment muscle force generation through multiple effects on the central nervous system, no studies have yet compared the effects of caffeine on force-generating capacity between younger and older men, who might respond differently due to age-related changes in the structures on which caffeine acts. In a double-blind, controlled trial, 22 younger (25 ± 5 years) and 21 older (68 ± 6 years) men were tested for isometric plantarflexor torque on two separate days (2–7 days apart) before and 60 min after ingesting 3 mg/kg (∼2 cups of coffee) of caffeine or placebo. No effects of caffeine ingestion on peak torque or rate of torque development were detected in either older or younger men. Therefore, 3 mg/kg of caffeine may not acutely counteract age-related decreases in force capacity of the functionally important plantarflexor muscles.

Vibratory (Tvib) and sustained (Tsust) torque responses to concurrent Achilles tendon vibration and neuromuscular electrical stimulation applied over the muscle belly (vib+stim) are used as indicators of motoneuron facilitation and, theoretically, persistent inward current strength. However, neuromuscular electrical stimulation (NMES) applied to the nerve trunk may potentiate motoneuronal excitability more than muscle belly NMES, yet it remains unclear whether NMES applied over the nerve evokes robust Tvib and Tsust responses when used during the vib+stim protocol. This study tested whether a nerve-targeted vib+stim protocol elicits Tvib and Tsust responses in the ankle plantar flexors with acceptable intra- and inter-session reliability. Fifteen men performed the vib+stim protocol with NMES applied over the tibial nerve three times across two sessions; twice in a single session (5-min apart) to test intrasession reliability and then again after 48 h to test intersession reliability. Intraclass correlation coefficients (ICC3,1), within-participant coefficients of variation (CV) and pairwise comparisons were used to verify relative and absolute reliability as well as systematic bias. Thirteen men presented Tvib and Tsust responses (response rate of 87%). Intrasession Tvib and Tsust ICCs were >0.73 but inter-session ICCs were 0.05), both intra- and inter-session CVs were large (>10%) for Tvib and Tsust. The Vib+stim protocol with NMES applied over the nerve evoked Tvib and Tsust in almost all participants, but presented a large intra- and inter-session variability. The method does not appear to be effective for assessing motoneuron facilitation in the plantar flexors.

The aim of the present study is to compare the effects of 12 weeks of resistance training with machines and elastic tubes on functional capacity and muscular strength in older women aged 60 years or over. The participants were randomized into two groups: a machine group (n = 23) and an elastic group (n = 20). They performed 12 weeks of progressive resistance training, twice a week, with similar exercises. Outcomes were assessed at three time points: baseline, postintervention, and 8 weeks after the end of the training. A significant intragroup effect was demonstrated for both groups at postintervention on functional tests and muscle strength. For the functional reach test and elbow flexion strength (180°/s), only the machine group demonstrated significant intragroup differences. No differences were observed between groups for any outcome. At the 8-week follow-up, functional capacity outcome values were maintained. The muscle strength outcome values decreased to baseline scores, without differences between groups.