An important epistemological problem has been faced by Exercise Physiologists. On one hand, one theory explains the fatigue through a ceiling effect of oxygen uptake. On the other hand, the new theory proposes that an encephalon mechanism would stop the effort before a catastrophic homeostasis failure. Many physiologists have looked for evidence to support their favourite theory even though the induction logic problem does not allow to prove whether truth is discovered; however, it is possible to prove that it does not occur. When some researchers fail to test their hypotheses, they use relativism to bring up their theories again. Noakes and his colleagues have based their theory on relativism, because it is impossible to refute by empirical observation. It also doesn't explain all phenomena that the oldest Hill's theory is able to explain. Noakes's theory isn't more accurate in its previsions. Noakes did not check whether the oxygen uptake plateau occurs in suitable tests to measure on the mouth what happens in the muscles. Finally, it doesn't propose new tests for the encephalon role during maximal effort, as that is expected in scientific work. For all of these reasons, it is possible to conclude there are no advantages in switching to the “Central Governor” theory.
Tendinopathy is a chronic degenerative musculoskeletal disorder that is common in both athletes and the general population. Exercise and extracorporeal shockwave therapy (ESWT) is among the most common treatments used to mediate tendon healing and regeneration. The review presents the current understanding of mechanisms of action of ESWT and exercise in isolation and briefly synthesises evidence of their effectiveness for various tendinopathies. The central purpose of the review is to synthesize research findings investigating the combination of ESWT and exercise for five common tendinopathies (plantar heel pain, rotator cuff, lateral elbow, Achilles, and patellar tendinopathy) and provide recommendations on clinical applicability. Collectively, the available evidence indicates that ESWT combined with exercise in the form of eccentric training, tissue-specific stretching, or heavy slow resistance training are effective for specific tendinopathies and can therefore be recommended in treatment. Whilst there are at present a limited number of studies investigating combined EWST and exercise approaches, there is evidence to suggest that the combination improves outcomes in the treatment of plantar heel pain, Achilles, lateral elbow, and rotator cuff tendinopathy. However, despite overall positive outcomes in patellar tendinopathy, the combined treatment has not been shown at present to offer additional benefit over eccentric exercise alone.
Alteration of the effective seat tube angle (ESTA) may affect muscle activation patterns of the lower limbs in cycling. There is conflicting evidence due to inadequate kinematic controls in previous studies. The primary aim of this study was to determine the muscle activity of seven lower limb muscles during alterations of the ESTA by altering the position of both the handlebars and saddle forwards or backwards by 3 cm while ensuring controlled kinematics. Secondly, to determine the effect on the saddle pressure indexes. Ten participants performed two 5 min electromyography (EMG) trials at 70% of peak power output (PPO) for three consecutive visits. There was a significant increase in muscle activity in the biceps femoris, gluteus maximus, and medial gastrocnemius with reductions in ESTA while a significant increase in tibialis anterior with increases in ESTA was observed. Saddle pressure indices demonstrated a significant change in frontal versus back pressure as well as mean pubic pressure with changes in ESTA. Alteration in the ESTA affects muscle activity in some, but not all of the lower limb muscles. Further research needs to be conducted to adequately understand the mechanism behind the differences in muscle activation.
Limb-loaded walking using ankle weights has been widely applied to increase exercise intensity in older adults. Examining changes in the activation pattern between proximal (RFP) and distal (RFD) regions of the rectus femoris (RF) muscle is key to clarifying gait deficits in older adults. The aim of this study was to determine regional neuromuscular regulation within the RF muscle following three-month limb-loaded walking in older adults. The study participants were 22 healthy older adults (69 ± 6.3 years) who walked at least 160 min per month. Surface electromyography (EMG) and motion capture were used to measure the neuromuscular activities of RFP and RFD and generate kinematic data on the left lower extremity on walking for 240 s at the preferred gait speed on a treadmill at pre- and post-intervention, respectively. Averaged rectified values (ARV) of RFP and RFD were normalized by maximum values of ARV during a gait cycle within ten consecutive gait cycles. Normalized ARV of RFP was greater than RFD at 30%-40% and 70%-90% of the gait cycle and hip joint flexion at 0%-100%, and the walking speed and swing timing at post-were greater than at pre-intervention (p < 0.05). No significant differences were noted in the RFP to RFD activity ratio (RFP/RFD ratio) between pre- and post-intervention, and there was no correlation between the RFP activity level and hip flexion angle in the swing phase (p > 0.05). The activity of RFP compared with RFD and hip joint flexion were increased following limb-loaded walking intervention in older adults.
To examine the contralateral repeated bout effect (CL-RBE) on muscle damage markers and motor unit (MU) control strategies, seventeen healthy adults performed two bouts of 60 eccentric contractions with elbow flexor (EF group; n = 9) or index finger abductor (IA group; n = 8) muscles, separated by 1 week. All participants randomly performed eccentric exercise on either the right or left arm or hand muscles, and muscle damage markers and submaximal trapezoid contraction tests were conducted pre, post, 1- and 2-day post eccentric protocol. One week after the first bout, the same exercise protocol and measurements were performed on the contralateral muscles. Surface electromyographic (EMG) signals were collected from biceps brachii (BB) or first dorsal interosseous (FDI) during maximal and submaximal tests. The linear regression analyses were used to examine MU recruitment threshold versus mean firing rate and recruitment threshold versus derecruitment threshold relationships. EMG amplitude from BB (bout 1 vs. bout 2 = 65.71% ± 22.92% vs. 43.05% ± 18.97%, p = 0.015, d = 1.077) and the y-intercept (group merged) from the MU recruitment threshold versus derecruitment threshold relationship (bout 1 vs. bout 2 = −7.10 ± 14.20 vs. 0.73 ± 16.24, p = 0.029, d = 0.513) at 50% MVIC were significantly different between two bouts. However, other muscle damage markers did not show any CL-RBE in both muscle groups. Therefore, despite changes in muscle excitation and MU firing behavior, our results do not support the existence of CL-RBE on BB and FDI muscles.
Adolescence is an important stage for brain maturation. To investigate the effect of different exercise doses on inhibitory control in adolescents aged 12 to 14-year old, an after-school exercise program was offered 5 days per week for 12 weeks during a school semester. Thirsty-four adolescents (17 boys) from the first six classes were randomly divided into low-dose exercise group (LE group, one 30-min aerobic exercise bout per day, n = 16) and high-dose exercise group (HE group, two 30-min aerobic exercise bouts per day, n = 18), while 23 adolescents (10 boys) in the control group (CON, zero 30-min exercise bout, n = 23) were from the last two classes. All the participants in different classes received the same physical education with the same contents, duration, and intensity at class. All the participants completed flanker tests and cardiorespiratory tests before and after exercise intervention. The HE group showed more significant improvements on inhibitory control and V˙O2peak than CON (p < 0.05). Changes in physical activity (PA) were significantly correlated with changes in interference scores (Spearman rho = -0.30, p < 0.05), V˙O2peak (Spearman rho = 0.31, p < 0.05), and BF percentage (Spearman rho = -0.32, p < 0.05). This study demonstrated that effect of exercise on inhibitory control in adolescents is dose-dependent, which highlights the need to focus on the exercise dose in daily life for improving cognition among adolescents.
Under the condition of normalized epidemic, how athletes train and compete well has been in the spotlight. This article reported the symptom, hospitalization and training situation of seven confirmed cases of coronavirus-disease-2019 (COVID-19) among Chinese national teams. Moreover, the paper summarized the experience of Chinese national teams in terms of epidemic prevention and control, treatment of infection, and safe return to play. Through a scientific combination of medication and non-medical treatment, seven athletes were all discharged from the hospital. These discharged athletes underwent strict isolation and scientific training before returning to sports teams. Before returning to play, continuous monitoring of physical and mental condition was required. All seven athletes returned to play safely and performed excellently. As for hosting large-scale sporting events, the entire enclosed-loop management from immigration to competition was proposed in this paper. This study could serve as a standard of epidemic prevention and control, treatment for infection and safe return to play during competition and training around the world.
Altered biomechanics due to amputation can contribute to substantial limitations, influencing sporting activities. Individuals with lower extremity amputations or congenital lower limb deficiency are encouraged to participate in para-sports. However, to compete in Paralympic sports, the candidate must have an impairment that results in lower extremity loss of function and meets or exceeds the sport's minimum impairment criteria (MIC). This review will focus on the MIC for competitive wheelchair tennis. Limb deficiency is known as one of the MIC used to regulate participation in competitive para-sports since it impacts gait, kinematics, and biomechanics of both the upper and lower body. Notwithstanding, it is questionable whether the MIC concerning limb deficiency is set at the correct level for determining eligibility for participating in Paralympic sports. This study aims to provide an overview of the evidence examining the impact of different partial foot amputation (PFA) levels on gait as a proxy for sporting performance. This scoping review will be based on a 6-step methodological framework and Preferred Reporting Items for Systematic Reviews and Meta-Analysis, extension for scoping reviews (PRISMA-ScR). Studies will be selected from PubMed, Embase, CINAHL, and SPORTDiscus. Two authors will screen the titles/abstracts independently. Selected studies will be scrutinised, and the same authors will extract data. Findings will be relevant to informing the evidence-based development of MIC for lower limb impairment after PFA and may be extrapolated to specific Paralympic sports, including wheelchair tennis. Results will be disseminated through scientific publications and conferences to audiences interested in Paralympic sports.