The aim of the study was to determine whether habitual minimalist shoe runners present with purported favorable running biomechanithat reduce running injury risk such as initial loading rate. Eighteen minimalist and 16 traditionally cushioned shod runners were assessed when running both in their preferred training shoe and barefoot. Ankle and knee joint kinetics and kinematics, initial rate of loading, and footstrike angle were measured. Sagittal ankle and knee joint stiffness were also calculated. Results of a two-factor ANOVA presented no group difference in initial rate of loading when participants were running either shod or barefoot; however, initial loading rate increased for both groups when running barefoot (p=0.008). Differences in footstrike angle were observed between groups when running shod, but not when barefoot (minimalist:8.71±8.99 vs. traditional: 17.32±11.48 degrees, p=0.002). Lower ankle joint stiffness was found in both groups when running barefoot (p=0.025). These findings illustrate that risk factors for injury potentially differ between the two groups. Shoe construction differences do change mechanical demands, however, once habituated to the demands of a given shoe condition, certain acute favorable or unfavorable responses may be moderated. The purported benefits of minimalist running shoes in mimicking habitual barefoot running is questioned, and risk of injury may not be attenuated.
In response to acute exercise, an array of metabolites, nucleic acids, and proteins are enriched in circulation. Collectively termed “exercise factors,” these molecules represent a topical area of research given their speculated contribution to both acute exercise metabolism and adaptation to exercise training. In addition to acute changes induced by exercise, the resting profile of circulating exercise factors may be altered by exercise training. Many exercise factors are speculated to be transported in circulation as the cargo of extracellular vesicles (EVs), and in particular, a sub-category termed “small EVs.” This review describes an overview of exercise factors, small EVs and the effects of exercise, but is specifically focused on a critical appraisal of methodological approaches and current knowledge in the context of changes in the resting profile small EVs induced by exercise training, and the potential bioactivities of preparations of these “exercise-trained” small EVs. Research to date can only be considered preliminary, with interpretation of many studies hindered by limited evidence for the rigorous identification of small EVs, and the conflation of acute and chronic responses to exercise due to sample timing in proximity to exercise. Further research that places a greater emphasis on the rigorous identification of small EVs, and interrogation of potential bioactivity is required to establish more detailed descriptions of the response of small EVs to exercise training, and consequent effects on exercise adaptation.
This study investigated within-subject variability in the circulating metabolome under controlled conditions, and whether divergent exercise training backgrounds were associated with alterations in the circulating metabolome assessed in resting samples. Thirty-seven men comprising of endurance athletes (END; body mass, 71.0 ± 6.8 kg; fat-free mass index, 16.9 ± 1.1 kg/m2), strength athletes (STR; 94.5 ± 8.8 kg; 23.0 ± 1.8 kg/m2), and recreationally active controls (CON; 77.6 ± 7.7 kg; 18.1 ± 1.0 kg/m2) provided blood samples after an overnight fast on two separate occasions controlled for time of day of sampling, recent dietary intake, time since last meal, and time since last exercise training session. A targeted profile of metabolites, performed using liquid chromatography and mass spectrometry on plasma samples, identified 166 individual metabolites and metabolite features, which were analyzed with intraclass correlation coefficients, a multilevel principal component analysis, and univariate t tests adjusted for multiple comparisons. The median intraclass correlation coefficient was .49, with 46 metabolites displaying good reliability and 31 metabolites displaying excellent reliability. No difference in the abundance of any individual metabolite was identified within groups when compared between visits, but a combined total of 44 metabolites were significantly different (false discovery rate <0.05) between groups (END vs. CON, 42 metabolites; STR vs. CON, 10 metabolites; and END vs. STR, five metabolites). Under similar measurement conditions, the reliability of resting plasma metabolite concentrations varies largely at the level of individual metabolites with ∼48% of metabolites displaying good-to-excellent reliability. However, a history of exercise training was associated with alterations in the abundance of ∼28% of metabolites in the targeted profile employed in this study.
Nugent, FJ, Flanagan, EP, Darragh, I, Daly, L, and Warrington, GD. The effects of high-repetition strength training on performance in competitive endurance athletes: A systematic review and meta-analysis. J Strength Cond Res 37(6): 1315-1326, 2023-The aim of this systematic review and meta-analysis was to evaluate the effects of high-repetition strength training (HRST) on performance in competitive endurance athletes. The methodology followed the Preferred Reporting Items for Systematic Review and Meta-Analysis protocol. A search of databases was performed until December 2020. Inclusion criteria were (a) competitive endurance athletes, (b) $4 weeks HRST intervention, (c) control or comparison group, (d) outcome measures of performance (either physiological or time trial performance), and (e) all experimental designs. Quality assessment was performed using the Physiotherapy Evidence Database (PEDro) scale. Of the 615 studies retrieved, 11 studies were included (216 subjects) and 9 studies provided sufficient data for the meta-analysis (137 subjects). The PEDro scale score had a mean of 5 of 10 points (range: 3-6). There was no significant difference between the HRST and control groups (g 5 0.35; 95% confidence interval [CI] 5 20.38 to 1.07; p 5 0.35) or HRST and low-repetition strength training (LRST) groups (g 5 0.24; 95% CI 5 20.24 to 0.72; p 5 0.33). The findings of this review and meta-analysis indicate that HRST does not result in improved performance over a 4-to 12-week period, and the results seem to be similar to LRST. The majority of studies involved recreational endurance athletes and had a mean duration of 8 weeks, which is a limitation of the findings. Future intervention studies should be . 12 weeks in duration and involve well-trained endurance athletes (maximal oxygen uptake [V Ȯ2max ] of .65 ml•kg 21 •min 22 ).
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