Food restriction alters salivary cortisol and α-amylase responses to a simulated weightlifting competition without significant performance modification

Motorcycling performance and sleepiness during an extended ride on a dynamic simulator: relationship with stress biomarkers

OBJECTIVE

Powered two-wheelers (PTW) make up a large proportion of fatal accidents. The aim of this study was to investigate the effects of time-of-day and total sleep deprivation (SD) on simulated motorcycling performance during extended riding sessions (60 min), while evaluating stress mechanisms.

APPROACH

A total of 16 healthy males participated in four simulated motorcycling sessions at 07:00, 11:00, 15:00 and 19:00, including city (8 min), country (2 min) and highway pathways (40 min), after a normal night of sleep and after total SD (30 h), in a randomized counterbalanced order. The recorded motorcycle parameters included: variation of lateral position, number of inappropriate line crossings (ILC), falls, riding errors, speed and speed limit violations. Subject parameters included the number of microsleeps in each pathway, the number of lapses during the 3-min psychomotor vigilance task (PVT-Brief version), and the Karolinska sleepiness scale (KSS) score. Saliva samples were used to assess cortisol (sC), α-amylase (sAA), and chromogranin-A (sCgA). ANOVAs and Pearson's correlation analysis were performed between these variables.

MAIN RESULTS

Most parameters were influenced by an interaction effect between 'Motorcycling pathways' × 'SD' (speed (p < 0.05), legal speed violations (p < 0.01), variation of lateral position (p < 0.001), falls (p < 0.001), EEG-microsleeps (p < 005)). An interaction effect between 'SD' × 'Time-of-day' influenced the number of ILCs (p < 0.01), sC (p < 0.05) and sCgA (p < 0.05) levels. SD affected KSS scores (p < 0.001) and PVT lapses (p < 0.05). The highest disturbances were associated with highway motorcycling simulation.

SIGNIFICANCE

Sleepiness due to circadian or SD and fatigue effects significantly affect riding and increase the risks involved with PTWs. The activation of both stress systems seems not sufficient to alleviate these deleterious effects.

Serum cortisol as a moderator of the relationship between serum testosterone and Olympic weightlifting performance in real and simulated competitions

Some equivocality exists regarding the effect of testosterone (T) on competitive performance with cortisol (C) implicated as a moderating factor. This study investigated whether C is moderating the T relationship with Olympic weightlifting (OWL) performance during real and simulated competitions. We monitored 105 male athletes (age 19.3±3.7 years); 46 during real OWL competitions (e.g., national age championships) and 59 across simulated events (e.g., talent identification). Serum T and C were assessed before warming up and within 15 minutes of event completion. Performance was indexed by the total combined load across the snatch and clean and jerk exercises. Hierarchical linear regression and simple slopes were employed to test the hormone and performance relationships. Pre-competition T (pre-T) and C (pre-C) were unrelated to OWL performance when controlling for competition type, time of day, age, and body mass (model=75.6% variance). However, the pre-T × pre-C interaction was significant (model=77% variance). Upon exploring this interaction, different pre-T and performance relationships emerged for males with high pre-C (β=-9.96) and low pre-C levels (β=9.04), with diverging slopes (p=0.006). The assessment of T changes and pre-C produced similar results. The association between male T and performance during OWL competition was determined by C activity, which could explain conflicting reports of T as a correlate of competitive abilities. Our results imply that T and C are not strictly anabolic and catabolic biomarkers of performance, respectively, but rather they exert complementary actions that could depend on task, situational and environmental needs.