Effects of exhaustive whole-body exercise and caffeine ingestion on muscle contractile properties in healthy men.

BACKGROUND: The influence of exhaustive whole-body exercise and caffeine ingestion on electromechanical delay (EMD) has been underexplored. This study investigated the effect of exhaustive cycling exercise on EMD and other parameters of muscle contractile properties and the potential ability of caffeine to attenuate the exercise-induced impairments in EMD and muscle contractile properties. METHODS: Ten healthy men cycled until exhaustion (88±2% of V̇O2max) on two separate days after ingesting caffeine (5 mg.kg-1 of body mass) or cellulose (placebo). Parameters of muscle contractile properties of the quadriceps muscles were assessed via volitional and electrically evoked isometric contractions, performed before and 50 minutes after ingestion of the capsules, and after exercise. Muscle recruitment during volitional contractions was determined via surface electromyography. RESULTS: Exhaustive cycling exercise did not affect volitional and relaxation EMD (P>0.05) but increased evoked EMD. In addition, the exhaustive cycling exercise also increased muscle recruitment at the beginning of volitional isometric muscle contraction (P<0.05). The peak twitch force, maximal rate of twitch force development, and twitch contraction time were all compromised after exhaustive cycling exercise (P<0.05). Acute caffeine ingestion had no effect on muscle contractile properties (P>0.05), except that caffeine increased twitch contraction time at postexercise (P<0.05). CONCLUSIONS: Exercise-induced decline in peripheral components of the EMD might be compensated by an increase in the muscle recruitment. In addition, acute caffeine ingestion had minimal influence on exercise-induced changes in muscle contractile proprieties.

Panax ginseng Supplementation Increases Muscle Recruitment, Attenuates Perceived Effort, and Accelerates Muscle Force Recovery After an Eccentric-Based Exercise in Athletes.

ABSTRACT: Cristina-Souza, G, Santos-Mariano, AC, Lima-Silva, AE, Costa, PL, Domingos, PR, Silva, SF, Abreu, WC, De-Oliveira, FR, and Osiecki, R. Panax Ginseng supplementation increases muscle recruitment, attenuates perceived effort, and accelerates muscle force recovery after an eccentric-based exercise in athletes. J Strength Cond Res 36(4): 991-997, 2022-The effect of Panax ginseng during and after an eccentric-based exercise is underexplored. In this study, we investigated the effect of Panax ginseng on muscle force and muscle excitation during an eccentric-based exercise and on subsequent muscle damage and delayed-onset muscle soreness (DOMS). Using a randomized, double-blind, crossover design, 10 male track and field athletes consumed Panax ginseng or placebo for 8 days. At the fifth day, they performed 4 sets until concentric failure of a half-squat exercise, with eccentric action increased by using an eccentric-inductor device attached to their knees. The rating of perceived exertion (RPE) and vastus lateralis electromyographic (EMG) activity was measured during the half-squat. Plasma lactate dehydrogenase (LDH) and creatine kinase (CK) concentrations, DOMS, and maximal isometric voluntary contractions (MIVCs) with EMG recording were measured at 24, 48, and 72 hours after the half-squat. Panax ginseng attenuated RPE and increased EMG during the sets. The MIVC remained reduced 48 hours after exercise in the placebo but returned to baseline 24 hours after exercise in the Panax ginseng, with values at 24 and 48 hours after exercise significantly higher in the Panax ginseng than in the placebo. The EMG during MIVC was higher in the Panax ginseng than in the placebo over the time points. No significant effect of Panax ginseng on LDH, CK, and DOMS was observed. These findings suggest that Panax ginseng increases muscle excitation and attenuates perceived effort during an eccentric-based exercise as well as accelerates the recovery of muscle force in well-trained athletes.

Maytenus ilicifolia Extract Increases Oxygen Uptake without Changes in Neuromuscular Fatigue Development during a High-Intensity Interval Exercise.

OBJECTIVE: We investigated the effects of acute ingestion of Maytenus ilicifolia extract on metabolic and cardiopulmonary responses during a high-intensity interval exercise (HIIE), and its consequence on neuromuscular fatigue. METHODS: Ten healthy men underwent a HIIE (4 x 4 min, 3 min recovery) one hour after ingesting 400 mg of Maytenus ilicifolia extract (MIE) or placebo. Oxygen uptake (V̇O2), dioxide carbon production (V̇CO2), ventilation (V̇E) and heart rate (HR) were measured throughout the HIIE. Maximal voluntary contraction (MVC), voluntary activation (VA), and evoked 1, 10 and 100 Hz force twitch were measured before supplementation (baseline), and before (pre-HIIE) and after the HIIE (post-HIIE). RESULTS: The V̇O2, V̇E, V̇E/V̇O2 ratio and HR increased progressively throughout the HIIE under both conditions (p < 0.05). MIE increased HR, however, at bouts 1 and 2 and mean V̇O2 during HIIE. The mean respiratory exchange ratio during recovery was also reduced with MIE (p < 0.05). MVC and evoked force at 1, 10 and 100 Hz declined similarly after HIIE, regardless of the condition (MIE: -18 ± 17%, -50 ± 15%, -61 ± 13% and -34 ± 10% vs. placebo: -19 ± 15%, -48 ± 16%, -58 ± 12 and -29 ± 11%, respectively, p < 0.05). There was no effect of exercise or MIE on VA (p > 0.05). CONCLUSION: MIE increases heart rate in the first bouts and mean oxygen uptake during HIIE without changes in neuromuscular fatigue development.

Correction: Effect of caffeine on neuromuscular function following eccentric-based exercise.

[This corrects the article DOI: 10.1371/journal.pone.0224794.].

Pre-planned Vs. Executed Real-Time Pacing Strategies during 3-km Race: Role of Rating Perceived Exertion.

Purpose: The aim of the study was to verify the agreement between preplanned and executed pacing during a 3-km race and determine whether adjustments are mediated by the rating of perceived exertion (RPE). Method: Thirteen young runners (eight males and five females, 17.5 ± 2.1 and 17.0 ± 1.6 years old, respectively) with national and international experience participated in the study. Before the simulated competition, the athletes informed of their preplanned pacing for the distance through a dashboard with the most common pacing profiles and were also asked to complete a questionnaire communicating their preplanned RPE for each lap of race. During 3-km, heart rate (HR), executed RPE and lap time were recorded. Results: Our results showed no significant association between preplanned and executed pacing (p = .631). Moreover, no significant difference between preplanned and executed RPE was found, including the analysis by laps and phases. RPE and HR increased over time during the race (p < .001). Conclusions: The athletes changed from their preplanned pacing, however, their RPE were similar in the preplanned and executed during the 3-km race. These findings indicate that the RPE could be responsible for adjustments in the pacing strategy.

Effect of caffeine on neuromuscular function following eccentric-based exercise.

This study investigated the effect of caffeine on neuromuscular function, power and sprint performance during the days following an eccentric-based exercise. Using a randomly counterbalanced, crossover and double-blinded design, eleven male jumpers and sprinters (age: 18.7 ± 2.7 years) performed a half-squat exercise (4 x 12 repetitions at 70% of 1 RM), with eccentric action emphasized by using a flexible strip attached to their knees (Tirante Musculador®). They ingested either a capsule of placebo or caffeine (5 mg.kg-1 body mass) 24, 48 and 72 h after. Neuromuscular function and muscle power (vertical countermovement-jump test) were assessed before and after the half-squat exercise and 50 min after the placebo or caffeine ingestion at each time-point post-exercise. Sprint performance was measured at pre-test and 75 min after the placebo or caffeine ingestion at each time-point post-exercise. Maximal voluntary contraction (overall fatigue) and twitch torque (peripheral fatigue) reduced after the half-squat exercise (-11 and -28%, respectively, P < 0.05) but returned to baseline 24 h post-exercise (P > 0.05) and were not affected by caffeine ingestion (P > 0.05). The voluntary activation (central fatigue) and sprint performance were not altered throughout the experiment and were not different between caffeine and placebo. However, caffeine increased height and power during the vertical countermovement-jump test at 48 and 72 h post half-squat exercise, when compared to the placebo (P < 0.05). In conclusion, caffeine improves muscle power 48 and 72 h after an eccentric-based exercise, but it has no effect on neuromuscular function and sprint performance.

Menstrual cycle alters training strain, monotony, and technical training length in young.

The menstrual cycle (MC) phases carry to several psychophysiological alterations; however, no study has investigated the impact of MC phases on training load or technical training. In the present study, we investigated the effect of the follicular phase (FP), ovulatory phase (OP), and luteal phase (LP) on training load and technical training in young athletes. Twelve female athletes performed regular daily training sessions with the rating of perceived exertion (RPE) and duration being registered every session. Training impulse (TRIMP), monotony and strain were calculated. MC symptoms, RPE, and duration were also measured during technical training, which was carried out on a specific day during each phase. The TRIMP was not affected by MC phases during regular training (p > .05), but training monotony and strain were higher in FP compared to OP (p < .05). During the technical training, MC phases did not affect RPE (p > .05), but the session was longer in both FP and LP, compared to OP (p < .05). MC symptoms were exacerbated in FP compared to both OP and LP (p < .05). These findings suggest that MC disorders were elevated during FP, which indicate that monitoring MC phases might provide important feedbacks for programming training and expected results during competitions.

Do biological maturity and performance influence the training load of track and field athletes? / A maturação sexual e o desempenho influenciam a carga de treinamento de atletas de atletismo?

Abstract It is necessary to clarify if BM and track and field performance can modulate the perception about RPE-session. The purpose of the present study was to verify if biological maturity and track and field-specific performance can be associated with training load (RPE-session method). Seventy-five young athletes (13-15 years old) of both genders participated in the present study. The experimental protocol lasted seven consecutive days. Performance tests (75-m running, long jump, 250-m running, shot put and 1000-m running) were made on the first day. After 48 hours, five days of track and field training it was prescribed, each day represents a training of each performance test. All training sessions had the same duration (120 min). The value of the training load was obtained multiplying the RPE value with training session duration (in minutes). For girls, the training load of 250-m training was correlated with biological maturity (r = -0.36, p = 0.02, n = 37) and specific performance (r = 0.33, p = 0.04, n = 37). All other analyzes indicate that biological maturity and track and field-specific performance do not influence the training load based on RPE-session method. Training load based on RPE-session is not influenced by biological maturity and track and field-specific performance, therefore can be used to control the training load of young track and field athletes. To girls it is necessary a care to control the training sessions intensity of 250-m running.

Resumo É necessário esclarecer se a maturação biológica e o desempenho no atletismo podem modular a PSE da sessão. O objetivo do presente estudo foi verificar se a maturidade biológica e o desempenho específico no atletismo podem estar associados à carga de treinamento (método de PSE da sessão). Setenta e cinco jovens atletas (13-15 anos) de ambos os sexos participaram do presente estudo. O protocolo experimental durou sete dias consecutivos. Testes de desempenho (75 m de corrida, salto em distância, 250 m de corrida, arremesso de peso e 1000 m de corrida) foram feitos no primeiro dia. Após 48 horas, cinco dias de treinamento de atletismo foram prescritos, cada dia representa um treinamento de cada teste de desempenho. Todas as sessões de treinamento tiveram a mesma duração (120 min). O valor da carga de treinamento foi obtido multiplicando o valor do PSE com a duração da sessão de treinamento (em minutos). Para as meninas, a carga de treinamento de 250 m foi correlacionada com a maturidade biológica (r = -0,36, p = 0,02, n = 37) e desempenho específico (r = 0,33, p = 0,04, n = 37). Todas as outras análises indicam que a maturidade biológica e o desempenho específico no atletismo não influenciam a carga de treinamento com base no método da PSE da sessão. A carga de treinamento com base na PSE da sessão não é influenciada pela maturidade biológica e desempenho específico no atletismo, portanto, pode ser usada para controlar a carga de treinamento de jovens atletas de atletismo. Para as meninas é necessário cuidado para controlar a intensidade das sessões de treino de 250m de corrida.

The Effects of Acute and Chronic Sprint-Interval Training on Cytokine Responses Are Independent of Prior Caffeine Intake.

We examined the effect of acute and chronic sprint interval training (SIT), with or without prior caffeine intake, on levels of exercise-induced inflammatory plasma cytokines [interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α]. Twenty physically-active men ingested either a placebo (n = 10) or caffeine (n = 10) 1 h before each SIT session(13-s × 30-s sprint/15 s of rest) during six training sessions (2 weeks). The early (before, immediately after, and 45 min after the exercise) and late (24 and 48 h after the exercise) cytokine and creatine kinase (CK) responses were analyzed for the first and last training sessions. Plasma IL-6 and IL-10 peaked 45 min after the exercise, and then returned to basal values within 24 h (p < 0.05) in both groups on both occasions (p > 0.05). On both occasions, and for both groups, plasma TNF-α increased from rest to immediately after the exercise and then decreased at 45 min before reaching values at or below basal levels 48 h after the exercise (p < 0.05). Serum CK increased from rest to 24 and 48 h post-exercise in the first training session (p < 0.05), but did not alter in the last training session for the PLA group (p > 0.05). Serum CK was unchanged in both the first and last training sessions for the CAF group (p > 0.05). Two weeks of SIT induced a late decrease in the IL-6/IL-10 ratio (p < 0.05) regardless of caffeine intake, suggesting an improved overall inflammatory status after training. In conclusion, a single session of SIT induces muscle damage that seems to be mitigated by caffeine intake. Two weeks of SIT improves the late SIT-induced muscle damage and inflammatory status, which seems to be independent of caffeine intake.

Factors determining 800-m running performance in young male athletes.

BACKGROUNDː The aim of the present study was to identify determinant variables on 800-m running performance in young male athletes derived from field tests and biological maturity. METHODSː A total of 89 athletes, aged between 13 and 15 years old, performed a 800-m running trial and a battery of tests which involved anthropometric measurements, a running anaerobic test (RAST), a flexibility test (sit-and-reach), a counter movement jump test and progressive test for aerobic fitness evaluation. A stepwise multiple regression model selected three independent variables to explain the variance in 800-m running performance trial: peak of aerobic speed (PAS), total time of all sprints (RAST) and predicted mature stature (PMS). RESULTSː The PAS speed explained 73.6% (P<0.01) of the variance, whereas the RAST and PMS accounted for additional 7.7% (P<0.01) and 0.9% (P<0.05), respectively. Taken together, these variables explained 82.2% of the overall 800-m running performance. CONCLUSIONSː The results indicate that the 800-m running performance might be explained mainly by aerobic (PAS) and anaerobic metabolisms (RAST). Beyond the traditional variables of performance in 800-m running trial, the biological maturity must be considered in regard of endurance performance of young athletes.