Objective This study aimed to investigate the acute and prolonged effects of anodal tDCS at different intensities applied over the primary motor cortex (M1) on knee muscular endurance. Methods Seventy healthy adults were randomized into four groups (1 mA, 2 mA, 3 mA, and sham) and received 10 sessions of 20 min tDCS over 4 weeks. The endurance index (EI), calculated as the ratio of work output during the last five to the first five of 15 maximal isokinetic contractions, was assessed at baseline (T0), immediately after the first session (T1), 24 h after the 10th session (T2), and at 1-week follow-up (T3). Results Among the 70 healthy participants, a non-linear dose-response pattern was observed. Only 2 mA tDCS produced significant enhancements in endurance, specifically for left knee flexion, outperforming sham stimulation at T1 and both sham and 3 mA stimulation at T2. Notably, 1 mA and 3 mA showed negligible or attenuated efficacy. Conclusions These findings underscore that tDCS-induced endurance gains are contingent upon optimized intensity and hemispheric targeting, rather than simply applying higher currents. The observed non-linear behavioral response pattern warrants further investigation with neurophysiological measures to elucidate the underlying cortical excitability dynamics.
Background Complex contrast training (CT) is the combination of traditional resistance (RT) and ballistic training (BT) exercises performed in a set-by-set manner. Most CT studies use traditional resistance exercise first, followed by ballistic exercise, in line with the post-activation performance enhancement rationale. However, whether altering the sequencing order with BT exercise performed first, followed by RT exercise, would produce different results is not clear. This study aimed to compare the effects of the sequencing order of RT and BT exercises on linear sprint, countermovement jump (CMJ), change-of-direction speed (CODS), 5-repetition maximum squat, and isometric mid-thigh pull. Methods Eighteen recreationally active female athletes (Tier 1) (age: 20.0 ± 1.4 years) completed a CT intervention with either RT followed by BT or BT followed by RT sequencing. Data were collected before and after a 4-week intervention, involving similar exercises and loads, with only the sequencing order differing. Results A significant main effect of time was observed for all performance variables after 4 weeks of training ( p < 0.001–0.019, η p 2 = 0.32–0.76). However, no significant interaction effects ( p = 0.101–1.000, η p 2 < 0.01–0.16) were observed. Conclusion This study's findings indicate that a 4-week CT can improve linear sprint, CMJ, CODS, and maximal isometric and dynamic strength in female participants, with no moderating effects of exercise order. Therefore, practitioners may use either sequencing format within CT, based on preference, to improve the physical performance of female participants.
Abstract Background Maximal effort conditioning activities, such as pushing isometric muscle action (PIMA) based push-ups, may acutely improve ballistic performance via the post-activation performance enhancement (PAPE) mechanism. The primary aim was to examine the effects of PIMA-based push-ups as a conditioning activity on medicine ball chest throw (MBCT) distance. The secondary aims were to determine the relationship between net peak force (NPF) produced during the PIMA push-up and MBCT distance, and assess the reliability of NPF measurement. Methods Eighteen male athletes were randomly assigned to a control (general warm-up) or an experimental condition (general warm-up + PIMA-based push-ups [3 × 5 s with 1-min rest]) in a crossover design. MBCT performance was assessed after 1 and 3-min of recovery following each condition. Results A significant main effect of condition ( p = 0.006) and time ( p < 0.001), and an interaction effect ( p = 0.042) were observed. MBCT distance was greater in the experimental condition at 3 min compared with all other conditions ( p ≤ 0.004), whereas no difference was observed at 1 min. A moderate correlation was found between NPF and MBCT distance at 1 min ( r = 0.477, p = 0.045), but not at 3 min ( p > 0.05). NPF showed excellent reliability (lower-bound intraclass correlation coefficient of 0.937, coefficient of variation of 9.7%). Conclusion PIMA-based push-ups may be used as a conditioning activity to potentiate upper-body muscle power (specifically for MBCT), and both exercises may be paired as an upper-body contrast-training exercise during complex-contrast training sessions. However, long-term adaptations of such a combination in a complex-contrast training format require further investigation.
Background: Sling exercises are highly effective for strengthening core muscles and improving neuromuscular control while reducing joint strain. However, few studies have investigated the clinical effects of sling exercises on patients initiated up to 8 weeks after total hip arthroplasty (THA). Purpose: This study was undertaken to investigate the effect of sling exercise on the functional recovery of patients after THA. Methods: The observer-blinded trial was conducted on thirty older patients (>= 65 years old) who had undergone THA. Participants were randomly and equally assigned to an experimental group (sling exercise program) or a comparison group (general exercise program). All participants received 30 min of comprehensive physiotherapy (5 & times;/week for 4 weeks). In addition, the experimental group received sling exercises, and the comparison group received general exercises (5 & times;/week for 4 weeks). Primary (stride lengths, stride times, stance times, and walking velocities) and secondary (pain scores and hip joint function scores) outcomes were measured before and after the 4-week training period. Results: The experimental group achieved greater increases in stride length and walking velocity than the comparison group (stride length, +19.5 vs. + 10.3 cm, p < .008, eta(2)= .880; walking velocity, +11.7 vs. + 8 cm/s, p<.016, eta(2)= .274, respectively). However, changes in stride times, stance times, pain scores, and hip joint function scores after intervention were similar in the two groups. Conclusion: Sling-based strengthening exercise may improve walking function recovery more than general exercise in older patients after total hip arthroplasty.
Background Sufficient scapular stability is essential for optimal upper-extremity function, with the serratus anterior (SA) playing a key role in both open and closed-chain exercises. However, compensatory pectoralis major (PM) overactivation often interferes with selective SA activation during the scapular protraction. This study compares muscle recruitment patterns between reciprocal inhibition (RI) and no-RI conditions. Objective The purpose of this study was to investigate the effects of a non-elastic band on the muscle activity of the PM and SA, as well as the SA/PM activity ratio, by comparing the RI condition and the no-RI condition during the scapular protraction. Methods Twenty healthy individuals performed the scapular protraction shoulder flexion under randomized no-RI and RI conditions. In the RI condition, isometric horizontal abduction resistance was applied via a non-elastic band to induce reciprocal inhibition of the PM. Surface EMG recorded SA and PM activities, analyzed using paired t-tests. Results SA activity showed no significant difference between the no-RI and RI conditions. In contrast, PM activity decreased significantly under the RI condition compared to the no-RI condition (p < 0.05). Consequently, the SA/PM ratio significantly increased, indicating that the RI protocol effectively suppressed compensatory PM activation while functional SA contribution was preserved (p < 0.05). Conclusion The scapular protraction under the RI condition might be an effective strategy for suppressing compensatory PM activation and increasing the SA/PM activity ratio. These findings suggest that this modified protocol might be a valuable clinical intervention for promoting selective scapular muscle balance.
