European Journal of Applied Physiology最新文献

Purpose: In this study, we investigated whether experimental knee pain alters lower limb kinematics and knee arthrokinematics during gait, and if this motor adaptation depends on the spatial characteristics of the painful stimulus.

Methods: Twenty-one participants walked on a treadmill for 60-s trials, either without stimulation or while experiencing painful electrical stimulation in the medial, lateral or anterior region of the knee. Perceived pain location was analyzed using pain drawing. Gait spatiotemporal parameters, lower limb kinematics, and dispersion of the knee helical axes on the sagittal plane were quantified for each trial and compared between conditions using ANOVAs with repeated measures or Friedman tests.

Results: Pain perception was localized in the area the stimulation was applied to. Compared to walking without pain, participants demonstrated reduced knee extension (1.5 ± 1.5 degrees, p = 0.002) and reduced hip extension (0.8 ± 1.1 degrees, p = 0.037) when pain was induced in the anterior region, but not medially or laterally. Anterior knee pain increased the mean distance of the helical axes during late stance (0.7 [0.3, 1.4], p = 0.010), while medial pain increased both mean distance (0.3 [0.1, 0.5], p = 0.037) and mean angle (1.2 ± 1.4, p = 0.010) during early swing.

Conclusion: Acute, experimental knee pain alters gait kinematics and increases the dispersion of the helical axis. These adaptations depend on the spatial characteristics of the painful stimulus. These adaptations may reflect an attempt of the central nervous system to protect the painful tissue while searching for a less painful movement strategy.

Purpose: Acute exercise can transiently enhance cognitive flexibility. The cognitive demand of firefighters makes it relevant to understand if on-shift exercise could produce similar improvements in cognitive performance during subsequent occupational tasks. Metrics of heart rate variability (HRV), such as time- and frequency-domain outcomes, may shed light upon the influence exercise has on cognition, as they discern information related to cardiac autonomic (sympathetic/parasympathetic) function. We aimed to determine if acute resistance and aerobic exercise impact cognitive flexibility during occupational tasks and its relation to HRV.

Methods: 32 participants completed a baseline Wisconsin Card Sorting Task (WCST) and three experimental trials: resistance exercise (RE), aerobic exercise (AE), or a rested control (CON). An occupational task assessment (OTA) including four rounds of 10 deadlifts and a 0.15-mile sandbag carry in an environmental chamber (35 °C/50% humidity) was completed after each trial. The second round was followed by the WCST. Repeated measures ANOVAs were used to analyze differences by condition.

Results: For the WCST, total, perseverative, and non-perseverative errors did not differ (ps > 0.39). Time-domain HRV metrics were not different (ps > 0.05). All frequency-domain metrics, other than low-frequency power, were not different (ps > 0.24). Low-frequency power was lower based on condition (p = 0.03). Post hoc analysis showed low-frequency power was lower following AE compared to RE and CON.

Conclusion: Results suggest an acute bout of on-shift aerobic or resistance exercise may not impact cognitive flexibility during subsequent simulated occupational tasks, despite depressed metrics of heart rate variability following aerobic exercise.