This study was aimed to analyze in detail how the fatigue effects to kinematic parameters of body weight squat exercise (BSQ) by dividing a squat cycle into four different regions. Twenty-one male athletes participated in this study. Participants were divided into two groups according to their lower limb muscle ratio (LLMR). The BSQ was performed until participants were unable to continue the exercise due to the fatigue. Linear and angular kinematics were obtained by motion analysis software which has high validity and reliability. There was no significant but had large effect size interaction between fatigue conditions and LLMR groups in terms of knee ROM in the extension phase and hip angular velocity in braking phase of the flexion (0.08 > p >0.05, 0.18 > > 0.16). Fatigue condition did not have a significant effect on the duration in the acceleration and braking phases of BSQ (p > 0.05). There were many significant main effects on kinematics in the different regions due to the fatigue (0.01 < p > 0.14). In the fatigue condition, there was a polynomial relationship between velocity of shoulder and hip joints (R²_flex = 0.82, R²_ext = 0.72) rather than linear (R²_flex = 0.64, R²_ext = 0.53) and coefficient correlations also decreased (r_flex = 0.88 to 0.80, r_ext = 0.92 to 0.73). The sticking region was observed in the non-fatigue condition and disappeared when fatigue occurred. These results suggest that LLMR may be taken into consideration in the squat exercises, joint tracking may vary for velocity-based squat training and pre-test for sticking region observation may be apply with the BSQ.

The primary aim of this study was to investigate relationships between the muscular force in the isometric bench press and squat movements and the Wingate anaerobic test (WanT) results for the upper and lower body. Secondary purpose was to investigate possible correlations between the WanT and the explosive isometric force. Eighteen healthy male volunteer athletes (age: 23.37 ± 1.65, height: 178.37 ± 5.67, body mass; 76.69 ± 3.73) with at least 2 years of strength training participated in the study. During the two test sessions, one-repetition maximum (1-RM), isometric squat and isometric bench press tests and anaerobic power tests with Wingate anaerobic power and arm ergometer were performed. Results of the study showed a high degree of correlation between isometric squat (Squatiso) and lower body Peak Power and Average Power (r (14) = 0.766, p < 0.001 and r (14) = 0.690, p < 0.003 respectively). However, there was no significant relationship between Squatiso and Fatigue Index (FI) (p > 0.05). In isometric bench press, there was also a high level of correlation between upper body peak power and average power (r (14) = 0.620, p < 0.01 and r (14) = 0.749, p < 0.001 respectively). These data can be used to classify the power capabilities of the athletes and determining the training loads to be used in achieving the training goals. In addition, periodic measurements of the maximum power and strength performances of the athletes with field tests and laboratory test batteries according to the characteristics of the sports branch can also provide significant contributions to the coaches and researchers.

The purpose of this study was to assess the differences in muscle activation (EMG) and body weight distribution (%BW) between suspension (TRX^™ push-up and TRX^™ inverted row) and conventional exercises (bench press and lying barbell row) using different contraction types (isometric and isotonic) and position variations (feet on the ground [FG] and feet on suspension device [FD]). It was also used to determine the intensity of the force applied to the straps of the suspension device corresponding to one repetition maximum (1-RM). Twelve male athletes (ages—24.5±4.2 years (mean±standard deviation [SD]); Height—181.0±6.8 cm; body mass—83.08±6.81 kg) participated in this study. Two suspension devices were used, one for the FD variation and one for the FG variation pectoralis major (PM) and triceps brachii (TRI) activations were assessed during the TRX^™ push-up and bench press exercises. Transversus trapezius (TRA) and biceps brachii (BB) activations were assessed during the TRX^™ inverted row and lying barbell row exercises. The results showed significant differences between exercises (FG and FD variations of TRX^™ push-up and bench press) in PM activities (isometric and isotonic) (p≤0.05). However, these differences were only observed during isometric TRI activation (p≤0.05). In the FG and FD variations of the TRX^™ inverted row and lying barbell row exercises, there were only differences in the isometric contractions of the TRA and BB (p≤0.05). In the suspension device of push-ups and inverted row for the FD variations, 70.5% and 72.64% of 1-RM intensity were obtained, respectively. Similar responses to training intensities and muscle activations can be obtained in suspension exercises and conventional exercises. FD variations of suspension exercises can be more effective in terms of muscle activations than FG variations, and isotonic suspension exercises increase exercise intensity more than isometric suspension exercises.

The purpose of this study was to analyse in detail body weight squat (BWS)’ fatigue effect on the range of motions (ROM) of the hip, knee, ankle and ground reaction forces (GRF). Twenty male recreational athletes (24.0 ± 3.1 years, 178.85 ± 7.12 cm and 78.7 ± 11.45 kg) participated in this study. BWS were performed on four load cell platforms until the participants failed to continue. Participants performed 73 ± 27 repetitions and the duration to complete of the repetitions was 140.72 ± 62.28 s during the BWS exercise. The forefoot and hindfoot of the feet were on two load cells, thus, there were two under each foot. All of the data collected was divided into three sections for analysis (24 ± 9 repetitions for each). In terms of GRF of the fore feet and hind feet, significant differences and medium to large effect size were found between each section (p = 0.006~0.040, ES = 0.693~0.492). No significant differences were found between right and left leg in all sections. Significant differences were found in the ROM of the hip between the sections of first-third (p = 0.044, ES = 0.482) and second-third (p = 0.034, ES = 0.510), the ROM of the knee first-third (p = 0.014, ES = 0.602) and second-third (p = 0.005, ES = 0.701) and for the ROM of the ankle first-second (p = 0.045, ES = 0.479). As a result, end-of-exercise fatigue caused an increase in the ROM of the hip, knee and ankle. Thus, it is observed that fatigue induced increased ROM, also increases the GRF towards the forefeet.

Article: The acute effects of different percentages of blood flow restrictions on all-out back squat exercise - Medicina dello Sport 2023 September;76(3):319-32 - Minerva Medica - Journals

Study aim: This study was aimed to analysis in detail how different tempos [2:0:2 (30 bpm), 1:0:1 (60 bpm), Explosive (EXP)] effect to ground reaction forces (vGRF) and joint kinematics of push-up exercise (PUP). Material and methods: Twenty-four recreationally male athletes (age: 24.9 ± 3.6 years) participated in this study. Kinetic and kinematic data were obtained by load-cells and a motion analysis software. Data was analysed from a single repetition which is showed peak vGRF of dominant side during PUP. Joint velocities were calculated by taking the difference between the descent and ascent phases. Results: There was significant difference between 2:0:2 (30 bpm) – EXP in terms of dominant side of shoulder (p ≤ 0.02) and between 1:0:1 (60 bpm) – EXP in the dominant elbow joint displacements (p ≤ 0.05). The velocity differences between the descent and ascent phases of shoulder and elbow joints were found statistically significant between tempos (p ≤ 0.05). In terms of range of motion (ROM) of right and left side, there was significant differences between tempos (p ≤ 0.001). No significant differences were found between all tempos in the ascent phase of right-left and left descent phase in terms of average vGRF (p > 0.05) except right descent average vGRF (p ≤ 0.02). Conclusions: In conclusion, right-left sides of ROM was used most effectively in 2:0:2 (30 bpm) and 1:0:1 (60 bpm) tempos. Less displacement was also observed in EXP and when tempo increased percentage of peak vGRF (at elbow flexion phase for right-left sides) to total repetition decreased. Highest ascent and descent phase velocity differences (for right-left sides) and highest peak vGRF (elbow flexion phase) observed in EXP. This study shows that increasing tempo will result in more unsteady joint kinematics and more vGRF, so if the goal is controlled and safe PUP, tempo should be slow.