Browsing by Author "Fleming, Colin"

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    Muscle oxygenation and performance adaptations in trained cyclists following a polarized and threshold training intervention
    (Stellenbosch : Stellenbosch University, 2023-12) Fleming, Colin; Terblanche, Elmarie; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Exercise, Sport and Lifestyle Medication.
    ENGLISH ABSTRACT: Training intensity, and its distribution within a training program, is a key variable in positively or negatively influencing athletic performance, through varying physiological adaptations stemming from different training intensities. However, experimental research investigating physiological adaptations to various training intensity distributions is scarce. As such, the purpose of this study was to examine the performance and peripheral adaptations to a polarized (POL) and a threshold (THR) training intervention in trained cyclists. Seventeen trained road and mountain bike cyclists, including men (n = 13) and women (n = 4), aged between 19 and 49 years, participated in this study. This study followed a pre-post design, with a random assignment of participants into two experimental groups: a POL or a THR training group. The pre- and post-tests included a ramp incremental test to exhaustion and a 30-s Wingate test, with concurrent cardiorespiratory, muscle oxygenation, power, heart rate, and blood lactate data collection. The intervention consisted of six weeks of polarized (80/0/20% in zone 1/2/3) or threshold (45/55/0% in zone 1/2/3) training. The findings of the present study indicate that both POL and THR training stimulate improvements in power output over a 6-week training period. There were no significant group*time interactions observed for any measured variable (p > 0.05), however, effect sizes were calculated to investigate the magnitude of differences after the training intervention. Both THR and POL displayed improvements in power output at LT2, and PPO, however the effect size was numerically greater after THR than POL training (ES = 0.54, 0.29). It was also found that the effect size of muscle oxygen utilization was greater after POL than THR at LT1, LT2, PPO, and after the 30-s Wingate (ES = 0.72, 0.91, 0.74, 1.76). The magnitude of change in VO₂max was larger for POL than THR (5.9% vs. 1.1% improvement, respectively; ES = 0.40). The THR group showed a greater numerical increase in effect size, compared to POL in anaerobic capacity and explosive power (ES = 0.34, 0.40). A moderate and a small numerical increase was observed in effect size in exercise economy at LT2 and PPO in THR, but not in POL (p > 0.05, ES = 1.11, 0.45). It is suggested that the observed improvement in power output at LT2 and PPO in the POL group may be attributed to peripheral aerobic adaptations, as indicated by an increase in O₂ utilization and VO₂max. Secondly, it is suggested that glycolytic adaptations may contribute to the improvement in power output at LT2 and PPO in the THR group, as reflected by a decrease in VO₂/W, along with increases in anaerobic capacity and explosive power. Over a 6-week period, neither POL nor THR appeared to be superior for improving endurance performance, but they may induce different adaptations.