Isokinetic muscle strength cannot be related to the odds ratio of musculoskeletal injuries in young elite wrestlers

Isometric and isokinetic strength of lower-limb muscles in female athletes during different phases of menstrual cycle: a causal-comparative study

BACKGROUND

Muscle strength is affected by different stages of the menstrual cycle in women. Since the strength of the lower limb muscles plays a significant role in the occurrence of anterior cruciate ligament injury, it seems necessary to study the strength of the lower limb muscles at different stages of this cycle to take preventive measures. Therefore, this study aimed to compare the isometric and isokinetic strength of lower limb muscles in female athletes at different menstrual cycle stages.

METHODS

The present study is of a causal-comparative type. Thirty-seven female athletes in anterior cruciate ligament injury high-risk disciplines participated in this study. Isometric and isokinetic knee extensors and flexors muscle strength status, including the traditional hamstrings/quadriceps (H/Q) ratios, were recorded at different stages of the menstrual cycle (follicular, ovulatory, luteal) by Biodex isokinetic dynamometry system 4. Then, the obtained results were analyzed by repeated measure analysis of variance.

RESULTS

Analysis of variance with repeated measures showed isokinetic and isometric strength in the knee flexor and extensor muscles at an angular velocity of 60˚/s in the ovulatory phase are higher than the follicular and luteal ones. The strength of the muscles declined during the follicular and luteal phases (p ≤ 0.05).

CONCLUSIONS

Due to the negative effect of the follicular and luteal stages of the menstrual cycle on the strength of the flexor and extensor muscles of the knee, the risk of anterior cruciate ligament injury may increase during this period. Therefore, it is recommended that all female coaches and athletes take preventive measures during this period.

Relationship between impulse and kinetic variables during jumping and landing in volleyball players

BACKGROUND

This study examined the relationships between impulse and kinetic variables during jumping and landing in elite young male volleyball players.

METHODOLOGY

Eighteen players were recruited and asked to jump on a force plate, which allowed for the direct extraction of jump and landing kinetic data. The data was then analysed using stepwise regression to explore the relationship between landing impulse and various kinetic variables.

RESULTS

Our findings revealed a significant positive relationship between the peak rate of force development concentric (PRFD _CON) and impulse at landing (β = 0.537, p = 0.02). In a secondary analysis, we found that PRFD _CON (β = 0.497, p = 0.01) and time to peak power concentric (TPPC) (β = 0.424, p = 0.04) were also positively correlated with landing impulse. Importantly, PRFD _CON and TPPC were the variables that had the most muscular predictive power for impulse at landing.

CONCLUSION

These findings offer crucial insights into the biomechanics of jumping and landing in elite young male volleyball players, informing the development of more effective training programs. Our study identifies PRFD _CON and TPPC as critical factors for improving landing impulse, emphasizing the need to consider multiple kinetic variables when designing training programs for explosive skills. These insights can help optimize performance and reduce the risk of injury in elite young male volleyball players.

The investigation of isokinetic knee strength and injury risks of taekwondo and wrestling athletes

Taekwondo and wrestling are two different Olympic combat sports that need lower extremity strength in different ways. During the training process that lasts for many years, the harmony in the leg muscles may be dissimilar. This study aims to determine (1) the extension and flexion strength values of elite taekwondo and wrestling athletes with similar physical and demographic characteristics and (2) the muscle balances formed after long-term taekwondo and wrestling training. This study was conducted with the voluntary participation of 20 elite taekwondo and wrestling athletes (Avg. age 20.4±1.27 years; experience: 10.6±1.98 years; height 176.65±5.86 cm; weight 72.96±6, 96 kg; BMI 23.35±1.47 kg/m2). Following the determination of the demographic and physical characteristics of the athletes, their isokinetic knee strengths were examined at an angular velocity of 600/s and compared between branches. Accordingly, the differences between the relative and average peak torque strengths of the athletes were significant in favour of the taekwondo players in the extension strength; On the other hand, the hamstring/quadriceps strength ratios of the taekwondo athletes were lower (p0.05). The study results showed that taekwondo players have higher extensor strength; Thus, extended taekwondo training allows more balanced hamstring/quadriceps muscle harmony than wrestling. Eventually, long-term wrestling training can cause muscle imbalances and injuries in athletes.

Judo specific fitness test performance variation from morning to evening: specific warm-ups impacts performance and its diurnal amplitude in female judokas

BACKGROUND

A number of specific tests are used to standardize competition performance. Specific Judo fitness test (SJFT) can be applied by considering the start of the competition qualifiers in the morning and the continuation of the final competitions in the evening. The improvement of test performances can be achieved with warm-up for elevating heart rate (HR) and muscle temperature such as raise, activate, mobilise, potentiate (RAMP) protocols.

PURPOSE

The aim of this study is to evaluate the effects of different warm-up protocols on SJFT at different times of the day in female judokas.

METHODS

Ten volunteer women participated in this study, who regularly participated in judo training for more than 5 years and actively competed in international competitions. Judokas completed SJFT, either after no warm-up, or RAMP protocols like specific warm-up (SWU), and dynamic warm-up for two times a day in the morning: 09:00-10:00 and in the evening: 16:00-17:00, with at least 2 days between test sessions. The following variables were recorded: throws performed during series A, B, and C; the total number of throws; HR immediately and 1 min after the test, and test index after different warm-ups.

RESULTS

When analyzed evening compared to the morning without discriminating three warm-up protocols, evening results statistically significant number of total throws performed during series A, B, and C, the total number of throws; HR immediately and 1 min after the test, and test index than morning results (p < 0.01). Moreover, RAMP protocols interaction with time have demonstrated an impact on SJFT for index [F₍₂₎ = 4.15, p = 0.024, η_p²: 0.19] and changes after 1 min HR [F_(1.370)= 7.16, p = 0.008, η_p²: 0.29]. HR after 1 min and test index results were statistically significant in favor of SWU (p < 0.05).

CONCLUSIONS

In conclusion, SJFT performance showed diurnal variation and judo performances of the judokas can be affected more positively in the evening hours especially after RAMP protocols.

Differences in Physical Characteristics of the Lower Extremity and Running Biomechanics Between Different Age Groups

(1) Background: The objective of this study was to determine physical and biomechanical changes in age groups upon running. (2) Method: 75 male adults (20–80s) participated in the study. Bone mineral density and lower extremity joint strength were measured according to age-increase targeting. Based on age, correlations among running characteristics, impulse, impact force, maximum vertical ground reaction force, loading rate, lower extremity joint 3D range of motion, joint moment, and power upon running motion were calculated. (3) Result: Older runners tended to show lower bone mineral density, extremity maximum strength, stride time, and stride distance, with smaller RoM and joint power of ankle and knee joints in the sagittal plane, compared with younger subjects. However, there were no significant correlations between age and impact variables (i.e., impulse, impact force, peak GRF, and loading rate) during running. (4) Conclusion: Older runners tend to show weaker physical strength characteristics, such as bone mineral density and muscle strength and lower joint functionality of ankle and knee joints during running, compared with younger runners. Therefore, strengthening the lower extremity muscle and improving dynamic joint function, especially for ankle joints, can be helpful for injury prevention during running.