ECSS Paris 2023: OP-MH37
INTRODUCTION: Night shift work, including shift work, forces workers to adopt irregular lifestyles that can adversely affect human physiology. In particular, impaired vascular function increases the risk of atherosclerotic disease, an important occupational health issue. While previous studies have shown that vascular endothelial function decreases after night shift work, it remains unclear whether this is temporary. A chronic decrease may lead to serious health risks such as cardiovascular disease and stroke, highlighting the need for effective lifestyle interventions. The aim of this study was to compare vascular endothelial function (flow-mediated dilation (FMD)) and structural markers of arterial stiffness [brachial-ankle Pulse Wave Velocity (baPWV), Ankle Brachial Index (ABI)] between the Day Work Group (DWG) and the Night Shift Work Group (NSWG) and to examine associations with lifestyle factors. METHODS: Forty healthy adult workers (20 each in DWG and NSWG), classified based on their current night shift work status. In a cross-sectional design, body composition, blood tests, vascular stiffness markers (baPWV, ABI) and FMD were assessed. Lifestyle factors, including dietary intake, physical activity, and sleep, were monitored for one week. Dietary intake was assessed using a smartphone app, and physical activity and sleep were assessed using an accelerometer. Group comparisons and correlations with lifestyle factors were analyzed. The Shapiro-Wilk test was used to test for normality; t-tests or Mann-Whitney U tests were used to compare groups, and Pearson or Spearman coefficients were used to analyze correlations. RESULTS: There were no significant differences in age, BMI or work history. NSWG had significantly higher body fat mass (14.9±5.0 kg vs. 11.8±3.3 kg, p=0.03) and body fat percentage (25.4±6.3% vs. 21.0±5.5%, p=0.02). NSWG showed higher hs-CRP (0.05±0.06 mg/dL vs. 0.01±0.02 mg/dL, p=0.03) and leptin levels (8.5±6.1 ng/mL vs. 5.3±3.3 ng/mL, p=0.02). Systolic and mean blood pressure were significantly higher in NSWG (p<0.05), but no differences were observed in baPWV or ABI. FMD was significantly lower in NSWG than in DWG (4.0±1.9% vs. 7.0±2.9%, p<0.01). In NSWG, FMD correlated negatively with sedentary behavior (≤1.5 METs; r=-0.47, p=0.04) and positively with light activity (1.6-2.9 METs; r=0.52, p=0.02). CONCLUSION: NSWG showed significantly lower FMD than DWG, with no differences in baPWV and ABI. This suggests that night shift work may chronically affect vascular endothelial function, whereas structural atherosclerotic changes require longer exposure. The association between FMD and physical activity suggests that lifestyle improvements may help reduce the risk of atherosclerosis in night shift workers. Future longitudinal and intervention studies are needed to evaluate the effects of increasing physical activity and reducing sedentary time on FMD.
Read CV Murata HiroyasuECSS Paris 2023: OP-MH37
INTRODUCTION: The Yo-Yo Intermittent Endurance Level 2 Test (YYIE2) is widely used to estimate cardiorespiratory fitness in recreational footballers using the aerobic performance construct. However, the shuttle-running nature of the YYIE2 protocol may pose challenges for overweight and untrained individuals. The present study examines the relationship between body composition parameters, assessed by dual-energy X-ray absorptiometry (DEXA), and aerobic performance and aerobic fitness measures (YYIE2 performance and VO₂peak, respectively) in recreational football players. METHODS: Three hundred male recreational footballers (age: 39±6 years, YYIE2: 427±167m, VO2peak: 38.57±6.28 mL.kg−1.min−1, body mass: 83.6±13.1 kg, stature: 173.7±6.2cm) participated in this cross-sectional study. Body composition parameters, including body mass, lean mass, fat mass percentage, android and gynoid fat mass, were measured using DEXA scans. YYIE2 performance was recorded as total distance covered, and cardiorespiratory fitness was determined via VO₂peak. Pearson correlation analysis was conducted to assess relationships between body composition variables and aerobic performance and aerobic fitness measures. RESULTS: YYIE2 performance was largely associated with VO₂peak (r=0.753, p<0.001). Moderate negative correlations were found between YYIE2 and body mass (r=-0.435, p<0.01), while VO₂peak demonstrated a large negative correlation with body mass (r=-0.530, p<0.01). Android fat mass was largely negatively correlated with both YYIE2 (r=-0.531, p<0.001) and VO₂peak (r=-0.612, p<0.001). Gynoid fat mass also showed moderate negative correlations with both YYIE2 (r=-0.350, p<0.01) and VO₂peak (r=-0.425, p<0.01). Fat mass percentage displayed large and very large negative correlations with YYIE2 (r=-0.674, p<0.001) and VO₂peak (r=-0.709, p<0.001), respectively. Correlations with lean mass were weaker, highlighting the dominant role of fat accumulation in limiting aerobic performance and aerobic fitness. CONCLUSION: This study highlights the significant impact of body composition on aerobic performance and aerobic fitness in recreational male footballers. Fat mass, particularly in the abdominal region, is a key limiting factor for both YYIE2 performance and VO₂peak. These findings suggest that targeted interventions aimed at reducing abdominal fat may lead to substantial improvements in aerobic fitness, aerobic performance and overall fitness in recreational football players. This work was funded by National Funds by FCT-Foundation for Science and Technology under the following project UI/04045.
Read CV Susana PóvoasECSS Paris 2023: OP-MH37
INTRODUCTION: Acute sleep loss can impair physical performance, with reduced sleep duration being consistently linked to decreased performance [1]. One common form of sleep loss, sleep fragmentation – characterized by repeated sleep interruptions – is a common problem among athletes [2], but its effects on neuromuscular performance have not been well researched and remain unclear. Thus, this study aims to examine the impact of induced sleep fragmentation on neuromuscular performance. METHODS: Fifteen trained adults (8M/7F, 25.8±2.4 years, 174.5±6.3 cm, 77.3±9.6 kg) participated in a randomized crossover study comparing two sleep conditions: fragmented (INT) and habitual sleep (CON), separated by a 5-night washout phase. Fragmentation was induced by having participants wake up every 2 hours for two consecutive nights, requiring them to turn on the lights and complete a brief task. Time in bed was standardized across conditions, based on a 7-night baseline average, and monitored using wearable technology. Following the sleep conditions, lower limb strength was assessed using an isokinetic dynamometer with a leg press adapter (ISOMED 2000). Maximal voluntary isometric contraction strength (MVIC) was tested at a 60º knee angle. Strength endurance was evaluated through a concentric-eccentric isokinetic test (20–90° knee ROM) at 90 mm/s with 15 all-out repetitions. Total work (Wtot) and a fatigue index (FI), reflecting the decline from the first three (MF3) to the last three repetitions, were separately calculated for the eccentric and concentric phases. Paired t-tests were used to compare all outcome measures between sleep conditions (α = 0.05). RESULTS: Time in bed (INT: 7.6±0.6h, CON: 7.8±1.0h, p=0.47) and time asleep (INT: 6.6±0.5h, CON: 6.8±0.9, p=0.38) did not differ significantly between conditions. No significant difference was found for MVIC (INT: 4.04±0.94kN, CON: 4.22±0.87kN, p=0.25, d=0.31). For concentric efforts, Wtot was significantly lower after INT (5.15±1.39kN) than after CON (5.32±1.33kN) (p=0.04, d=0.59). Despite no change in concentric FI (INT: 54.1±12.2%, CON: 52.8±13.1%, p=0.57, d=0.15), the concentric MF3 was lower after INT (2.16±0.51kN) than after CON (2.29±0.47kN) (p=0.04, d=0.57) indicating a higher starting force level after CON nights. During the eccentric efforts, no significant differences were observed for Wtot (INT: 6.68±1.91kJ, CON: 6.84±1.68 kJ, p=0.33, d=0.26), FI (INT: 49.1±13.7%, CON: 46.1±11.1%, p=0.38, d=0.23) and MF3 (INT: 3.21±0.76kN, CON: 3.45±0.82kN, p=0.09, d=0.48). CONCLUSION: Even with unchanged total sleep duration, the sleep fragmentation intervention caused a notable decline in concentric force production during an isokinetic leg press task. The fatigue index remained stable between conditions, but the participants produced greater concentric force at the beginning of the trial and greater total work. No changes were observed for the MVIC and eccentric outcome measures. 1 Craven et al., Sports Medicine, 2022 2 Vitale et al., Int J Spo Med, 2019
Read CV Michelle SluneckoECSS Paris 2023: OP-MH37