Journal of Sport and Health Science最新文献

Purpose: This study aimed to evaluate the relationship between peak tibial acceleration and peak ankle joint contact forces in response to stride length manipulation during level-ground running.

Methods: Twenty-seven physically active participants ran 10 trials at preferred speed in each of 5 stride length conditions: preferred, ±5%, and ±10% of preferred stride length. Motion capture, force platform, and tibial acceleration data were directly measured, and ankle joint contact forces were estimated using an inverse-dynamics-based static optimization routine.

Results: In general, peak axial tibial accelerations (p < 0.001) as well as axial (p < 0.001) and resultant (p < 0.001) ankle joint contact forces increased with stride length. When averaged within the 10 strides of each stride condition, moderate positive correlations were observed between peak axial acceleration and joint contact force (r = 0.49) as well as peak resultant acceleration and joint contact force (r = 0.51). However, 37% of participants illustrated either no relationship or negative correlations. Only weak correlations across participants existed between peak axial acceleration and joint contact force (r = 0.12) as well as peak resultant acceleration and ankle joint contact force (r = 0.18) when examined on a step-by-step basis.

Conclusion: These results suggest that tibial acceleration should not be used as a surrogate for ankle joint contact force on a step-by-step basis in response to stride length manipulations during level-ground running. A 10-step averaged tibial acceleration metric may be useful for some runners, but an initial laboratory assessment would be required to identify these individuals.

Purpose: This study aimed to examine the linkage between gut microbiome taxa and exercise-induced inflammation.

Methods: Twenty-five cyclists provided 4 stool samples during a 10-week period and cycled vigorously for 2.25 h at 67% maximal oxygen uptake (VO_2max) in a laboratory setting. Blood samples were collected pre- and post-exercise, with additional samples collected at 1.5-h, 3-h, and 24-h post exercise. Primary outcomes included stool microbiome composition and alpha diversity via whole genome shotgun (WGS) sequencing (averaged from 4 stool samples) and a targeted panel of 75 plasma oxylipins. A total of 5719 taxa were identified, and the 339 that were present in more than 20% of stool samples were used in the analysis. Alpha diversity was calculated by evenness, and the Analysis of Composition of Microbiomes (ANCOM) differential abundance analysis was performed using Quantitative Insights Into Microbial Ecology-2 (QIIME2). A composite variable was calculated from 8 pro-inflammatory oxylipins generated from arachidonic acid (ARA) and cytochrome P-450 (CYP).

Results: ARA-CYP oxylipins were significantly elevated for at least 3-h post-exercise (p < 0.001); they were strongly and positively related to Prevotella copri (P. copri) abundance (R² = 0.676, p < 0.001) and negatively related to gut microbiome alpha diversity (R² = 0.771, p < 0.001).

Conclusion: This analysis revealed for the first time a novel, positive relationship between gut microbiome P. copri abundance in cyclists and post-exercise pro-inflammatory oxylipins. These data demonstrate that about two-thirds of the wide variance in inflammation following prolonged and intensive exercise is largely explained by the abundance of a single gut bacterial species: P. copri.

Background: Fat loss mainly conveys the benefits of caloric restriction for people living with type 2 diabetes. The literature is equivocal regarding whether exercise facilitates fat loss during caloric restriction. This analysis aimed to assess the dose-response effects of exercise in combination with a caloric restriction on fat mass (FM) and FM percentage (FM%) in persons with diagnosed type 2 diabetes.

Methods: In this secondary analysis of a 4-armed randomized trial, 82 persons living with type 2 diabetes were randomly allocated to the control group (CON) (n = 21), diet control (DCON) (25% caloric restriction; n = 20), diet control and exercise 3 times per week (MED) (n = 20), or diet control and exercise 6 times per week (HED) (n = 21) for 16 weeks. The primary analysis was the change in FM% points. Secondary analyses included fat-free mass and visceral adipose tissue (VAT) volume (cm³).

Results: FM% decreased compared to CON by a mean difference of -3.5% (95% confidence interval (95%CI): -5.6% to -1.4%), -6.3% (95%CI: -8.4% to -4.1%), and -8.0% (95%CI: -10.2% to -5.8%) for DCON, MED, and HED, respectively. Compared to DCON, MED, and HED decreased FM% by -2.8% (95%CI: -4.9% to -0.7%) and -4.5% (95%CI: -6.6% to -2.4%), respectively. The difference in FM% between HED and MED was -1.8% (95%CI: -3.9% to 0.4%). DCON and MED decreased fat-free mass compared to CON, whereas HED preserved fat-free mass (-0.2%; 95%CI: -2.0% to 1.7%). Compared to CON, VAT volume decreased by -666.0 cm³ (95%CI: -912.8 cm³ to -385.1 cm³), -1264.0 cm³ (95%CI: -1679.6 cm³ to -655.9 cm³), and -1786.4 cm³ (95%CI: -2264.6 cm³ to -1321.2 cm³) more for DCON, MED, and HED, respectively. HED decreased VAT volume more than DCON (-1120.4 cm³; 95%CI: -1746.6 cm³ to -639.4 cm³) while the remaining comparisons did not reveal any differences.

Conclusion: All interventions were superior in reducing FM% compared to standard care. Adding exercise to a caloric restriction was superior in reducing FM% compared to a caloric restriction alone.

Background: Residual force enhancement (rFE), defined as increased isometric force following active lengthening compared to a fixed-end isometric contraction at the same muscle length and level of activation, is present across all scales of muscle. While rFE is always present at the cellular level, often rFE "non-responders" are observed during joint-level voluntary contractions.

Methods: We compared rFE between the joint level and single fiber level (vastus lateralis biopsies) in 16 young males. In vivo voluntary knee-extensor rFE was measured by comparing steady-state isometric torque between a stretch-hold (maximal activation at 150°, stretch to 70°, hold) and a fixed-end isometric contraction, with ultrasonographic recording of vastus lateralis fascicle length (FL). Fixed-end contractions were performed at 67.5°, 70.0°, 72.5°, and 75.0°; the joint angle that most closely matched FL of the stretch-hold contraction's isometric steady-state was used to calculate rFE. The starting and ending FLs of the stretch-hold contraction were expressed as % optimal FL, determined via torque-angle relationship.

Results: In single fiber experiments, the starting and ending fiber lengths were matched relative to optimal length determined from in vivo testing, yielding an average sarcomere excursion of ∼2.2-3.4 µm. There was a greater magnitude of rFE at the single fiber (∼20%) than joint level (∼5%) (p = 0.004), with "non-responders" only observed at the joint level.

Conclusion: By comparing rFE across scales within the same participants, we show the development of the rFE non-responder phenomenon is upstream of rFE's cellular mechanisms, with rFE only lost rather than gained when scaling from single fibers to the joint level.

Background: Large Language Models (LLMs) have gained much attention and, in part, have replaced common search engines as a popular channel for obtaining information due to their contextually relevant responses. Osteoarthritis (OA) is a common topic in skeletal muscle disorders, and patients often seek information about it online. Our study evaluated the ability of 3 LLMs (ChatGPT-3.5, ChatGPT-4.0, and Perplexity) to accurately answer common OA-related queries.

Methods: We defined 6 themes (pathogenesis, risk factors, clinical presentation, diagnosis, treatment and prevention, and prognosis) based on a generalization of 25 frequently asked questions about OA. Three consultant-level orthopedic specialists independently rated the LLMs' replies on a 4-point accuracy scale. The final ratings for each response were determined using a majority consensus approach. Responses classified as "satisfactory" were evaluated for comprehensiveness on a 5-point scale.

Results: ChatGPT-4.0 demonstrated superior accuracy, with 64% of responses rated as "excellent", compared to 40% for ChatGPT-3.5 and 28% for Perplexity (Pearson's χ² test with Fisher's exact test, all p < 0.001). All 3 LLM-chatbots had high mean comprehensiveness ratings (Perplexity = 3.88; ChatGPT-4.0 = 4.56; ChatGPT-3.5 = 3.96, out of a maximum score of 5). The LLM-chatbots performed reliably across domains, except for "treatment and prevention" However, ChatGPT-4.0 still outperformed ChatGPT-3.5 and Perplexity, garnering 53.8% "excellent" ratings (Pearson's χ² test with Fisher's exact test, all p < 0.001).

Conclusion: Our findings underscore the potential of LLMs, specifically ChatGPT-4.0 and Perplexity, to deliver accurate and thorough responses to OA-related queries. Targeted correction of specific misconceptions to improve the accuracy of LLMs remains crucial.