Lower limb fatigue reduces muscle strength, alters joint biomechanics, affects gait, and increases injury risk. In addition, it is of great clinical significance to explore local muscle fatigue or weakness caused by fatigue to understand its compensatory effect on the ipsilateral or contralateral joints. We systematically searched multiple databases, including five databases, using key terms such as “Muscle Fatigue” and “Gait”. Only studies that experimentally induced fatigue through sustained muscle activities in healthy adults were included. This review examined 11 studies exploring the effects of lower limb muscle fatigue on gait and lower limb biomechanics. The findings indicated that muscle fatigue significantly influenced spatiotemporal parameters, joint angles, and moments. Most studies that were reviewed reported an increase in step width and a decrease in knee joint moments following fatigue. Additionally, muscle activation levels tended to decline. In summary, compensatory mechanisms can lead to new walking strategies, such as increasing step width or enhancing the strength of muscles in adjacent joints. These adjustments impact dynamic balance differently: wider steps may enhance medial–lateral stability, while reduced muscle strength could lead to higher heel contact velocity and longer slip distances. Although these changes might influence dynamic balance, compensatory strategies may help mitigate the overall effect of fall risk. Future studies should use appropriate protocols, such as moderate or severe fatigue interventions with isokinetic dynamometry.

Background: This study aimed to examine the associations between dietary patterns and physical fitness among Chinese children, adolescents, and young adults, and to investigate the differences in dietary patterns and physical fitness between urban and rural Chinese children and adolescents. Methods: The data were obtained from the Chinese National Survey on Students’ Constitution and Health (CNSSCH). The final analysis included 200,276 participants from fourth grade to the fourth year of undergraduate study from urban and rural China. Statistical analyses were conducted using the R software (version 4.4.3). Group differences were examined using t-tests, and multivariable linear regression models were applied to evaluate associations between dietary patterns and physical fitness indicators, adjusting for sex, educational stage, socioeconomic status, and physical activity. Interaction terms were included to assess urban–rural differences. Results: Regular consumption of breakfast, eggs, and dairy products was positively associated with muscular strength, endurance, flexibility, and speed (p < 0.05), while higher intake of sugar-sweetened beverages was negatively associated with flexibility and muscular performance (p < 0.001). These associations were stronger among rural students, who benefited more from healthy dietary patterns but were also more vulnerable to the adverse effects of sugary beverages on BMI, lung capacity, and strength. Conclusions: This study explored the associations between dietary patterns and physical fitness among children, adolescents, and young adults in Chinese urban and rural areas. Our findings suggest that regular consumption of breakfast, eggs, and dairy products is positively associated with muscular strength, speed, endurance, and coordination, whereas frequent intake of sugary beverages is associated with poorer physical fitness. These associations appeared to differ between urban and rural populations: rural students may benefit more from nutrient-rich dietary patterns but also seem more vulnerable to the adverse associations of sugary beverages.

Countermovement jump (CMJ) is a key test for evaluating lower-limb neuromuscular function, and accurate measurement of countermovement depth (CMD) and countermovement velocity (CMV) is critical for determining optimal performance. However, the measurement validity and reliability of CMD and CMV—particularly when obtained from force plates (FP) and linear position transducers (LPT)—have remained uncertain. This study determined the validity and reliability of FP and LPT for measuring CMD and CMV. Twenty-eight male recreational athletes performed the CMJ test, and the variables were synchronously acquired by Motion Capture (MC), FP, and LPT. The test was divided into two sessions, with participants completing three maximal effort CMJs per session, and the second session occurred more than 48 h after the first. The reliability was evaluated using the intraclass correlation coefficient (ICC), and the validity was evaluated with linear Pearson’s correlation coefficient (r), one-way ANOVA with repeated measures, and Bland–Altman plots. The reliability results for FP and LPT indicated good to excellent (ICC = 0.809–0.900). Compared with MC, the FP showed a high to very high correlation (r = 0.894–0.937), and the LPT showed a high correlation (r = 0.721–0.726). When precise quantification of CMD/CMV is required, FP should be preferred. If only an LPT is available, it is best used for within-athlete longitudinal monitoring with a consistent setup, and cross-device comparisons should be avoided.

This study used stair-embedded force plates to investigate the effects of lower-limb muscle fatigue on dynamic postural control during stair descent in young adults. Twenty-five healthy male adults (age = 19.2 ± 1.5 years) were tested for stair descent gait in pre-fatigue and post-fatigue conditions. To induce fatigue, participants performed a sit-to-stand task. The kinematic and kinetic data were collected synchronously, and gait parameters were analyzed. Data were analyzed using one-dimensional statistical parametric mapping (SPM1d) and paired t-tests in SPSS. After fatigue, the right knee flexion angle increased significantly across all phases (0–14%, p < 0.001; 14–19%, p = 0.032; 42–50%, p = 0.023; 60–65%, p = 0.022; 80–100%, p = 0.012). Additionally, the step width widened notably (p < 0.001), while the proportion of the swing phase decreased (p = 0.030). During the event of right-foot release, the left knee flexion (p = 0.005) and ankle dorsiflexion (p = 0.001) angle increased significantly, along with a larger left ankle plantarflexion moment (p = 0.032). After fatigue, the margin of stability in the anterior–posterior direction (MoS-AP) (p = 0.002, p = 0.014) and required coefficient of friction (RCOF) (p = 0.031, p = 0.021) significantly increased at the left-foot release and right-foot release moments. This study demonstrates that lower-limb muscle fatigue increases dynamic instability during stair descent. Participants adopted compensatory strategies, including widening step width, reducing single-support duration, and enhancing ankle plantarflexion to offset knee strength deficits. These adaptations likely reflect central nervous system mechanisms prioritizing stability, highlighting the ankle’s compensatory role as a potential target for joint-specific interventions in fall prevention and rehabilitation. Future studies should investigate diverse populations, varying fatigue levels, and comprehensive neuromuscular indicators.

The objective of this study was to investigate the impact of localized muscle fatigue (LMF) in the hip, knee, and ankle muscle groups on stair ascent biomechanics, with a focus on identifying compensatory mechanisms following fatigue. Twenty-five participants were fatigued using an isokinetic dynamometer to induce unilateral muscle fatigue in the hip extension, knee extension, and ankle plantarflexion muscles through repetitive isokinetic contractions. We collected stair ascent data before fatigue and after three different fatigue protocols, simultaneously collecting kinematic, kinetic, and electromyographic data. The effects of different muscle fatigue conditions on stair ascent performance were assessed using one-way repeated-measures ANOVA. Key findings revealed that hip fatigue narrowed step width and increased ankle dorsiflexion. Knee fatigue reduced knee extensor moments on the fatigued side and increased hip extension moments bilaterally. Ankle fatigue decreased plantar flexion and increased hip extension moments. Electromyographic data confirmed corresponding shifts in muscle activation. Collectively, the results suggest that localized lower-limb fatigue may alter stair ascent biomechanics in a joint-specific manner. The observed changes in joint moments and muscle activation may reflect a bidirectional pattern of inter-joint compensation, with proximal-to-distal or distal-to-proximal adjustments depending on the fatigued joint. These findings suggest that mechanical and neuromuscular demands may be redistributed across lower-limb joints under acute fatigue conditions; however, given that this study was conducted in healthy young males, the relevance of these findings to stair-related instability or fall risk in more vulnerable populations should be examined in future studies.