Prevalence of low energy availability in 25 New Zealand elite female rowers - A cross sectional study.

OBJECTIVES: To quantify energy availability (EA) in elite female rowers, determine its association with bone mineral density (BMD), and examine the ability of the low energy availability in females-questionnaire (LEAF-Q) and brief eating disorder in athletes-questionnaire (BEDA-Q) to distinguish between low and normal EA. DESIGN: Observational cross-sectional study. METHODS: Twenty-five elite female rowers participated in the study. EA was calculated by means of a 4-day food intake diary and analysis of training load. Low energy availability (LEA) was defined as EA <30 kCal * kg-1 * FFM-1 * day-1. Dual-energy X-ray absorptiometry (DXA) was used to assess fat free mass (FFM) and BMD Z-scores. LEA risk was assessed using the LEAF-Q and BEDA-Q. RESULTS: The mean EA was 23.2 ±â€¯12.2 kCal * kg-1 * FFM-1 * day-1. Prevalence of LEA was 64 %. The mean BMD Z-score was 1.6 ±â€¯0.6 (range: 0.7 to 2.9). Athletes with LEA had a significantly higher BEDA-Q score than the group with normal EA (mean 0.30 ±â€¯0.17 vs. 0.09 ±â€¯0.11, P < 0.05), but LEAF-Q score was not different between groups (mean 10.4 ±â€¯4.6, 8.2 ±â€¯4.5, P = 0.29). CONCLUSION: Low energy availability is common amongst elite female rowers in New Zealand and is positively correlated with higher scores on the BEDA-Q. Bone mineral density was normal irrespective of EA status.

Diagnostic Accuracy of a Portable ECG Device in Rowing Athletes.

BACKGROUND: Athletes can experience exercise-induced transient arrythmias during high-intensity exercise or competition, which are difficult to capture on traditional Holter monitors or replicate in clinical exercise testing. The aim of this study was to investigate the reliability of a portable single channel ECG sensor and data recorder (PluxECG) and to evaluate the confidence and reliability in interpretation of ECGs recorded using the PluxECG during remote rowing. METHODS: This was a two-phase study on rowing athletes. Phase I assessed the accuracy and precision of heart rate (HR) using the PluxECG system compared to a reference 12-lead ECG system. Phase II evaluated the confidence and reliability in interpretation of ECGs during ergometer (ERG) and on-water (OW) rowing at moderate and high intensities. ECGs were reviewed by two expert readers for HR, rhythm, artifact and confidence in interpretation. RESULTS: Findings from Phase I found that 91.9% of samples were within the 95% confidence interval for the instantaneous value of the changing exercising HR. The mean correlation coefficient across participants and tests was 0.9886 (σ = 0.0002, SD = 0.017) and between the two systems at elevated HR was 0.9676 (σ = 0.002, SD = 0.05). Findings from Phase II found significant differences for the presence of artifacts and confidence in interpretation in ECGs between readers' for both intensities and testing conditions. Interpretation of ECGs for OW rowing had a lower level of reader agreement than ERG rowing for HR, rhythm, and artifact. Using consensus data between readers' significant differences were apparent between OW and ERG rowing at high-intensity rowing for HR (p = 0.05) and artifact (p = 0.01). ECGs were deemed of moderate-low quality based on confidence in interpretation and the presence of artifacts. CONCLUSIONS: The PluxECG device records accurate and reliable HR but not ECG data during exercise in rowers. The quality of ECG tracing derived from the PluxECG device is moderate-low, therefore the confidence in ECG interpretation using the PluxECG device when recorded on open water is inadequate at this time.

Central activation, metabolites, and calcium handling during fatigue with repeated maximal isometric contractions in human muscle.

PURPOSE: To determine the roles of calcium (Ca2+) handling by sarcoplasmic reticulum (SR) and central activation impairment (i.e., central fatigue) during fatigue with repeated maximal voluntary isometric contractions (MVC) in human muscles. METHODS: Contractile performance was assessed during 3 min of repeated MVCs (7-s contraction, 3-s rest, n = 17). In ten participants, in vitro SR Ca2+-handling, metabolites, and fibre-type composition were quantified in biopsy samples from quadriceps muscle, along with plasma venous [K+]. In 11 participants, central fatigue was compared using tetanic stimulation superimposed on MVC in quadriceps and adductor pollicis muscles. RESULTS: The decline of peak MVC force with fatigue was similar for both muscles. Fatigue resistance correlated directly with % type I fibre area in quadriceps (r = 0.77, P = 0.009). The maximal rate of ryanodine-induced Ca2+-release and Ca2+-uptake fell by 31 ± 26 and 28 ± 13%, respectively. The tetanic force depression was correlated with the combined reduction of ATP and PCr, and increase of lactate (r = 0.77, P = 0.009). Plasma venous [K+] increased from 4.0 ± 0.3 to 5.4 ± 0.8 mM over 1-3-min exercise. Central fatigue occurred during the early contractions in the quadriceps in 7 out of 17 participants (central activation ratio fell from 0.98 ± 0.05 to 0.86 ± 0.11 at 1 min), but dwindled at exercise cessation. Central fatigue was seldom apparent in adductor pollicis. CONCLUSIONS: Fatigue with repeated MVC in human limb muscles mainly involves peripheral aspects which include impaired SR Ca2+-handling and we speculate that anaerobic metabolite changes are involved. A faster early force loss in quadriceps muscle with some participants is attributed to central fatigue.

Chronic weight control impacts on physiological function and bone health in elite jockeys.

The aim of this study was to evaluate the impact of weight restrictions on physiological function and bone health in a group of horse racing jockeys. Twenty-seven elite male jockeys participated in this study (17 flat jockeys; 10 national hunt jockeys). Participants completed a range of measurements including anthropometry, hydration analysis, bone mineral density assessment, and musculoskeletal screening. Fifty-nine percent of flat and 40% of national hunt jockeys showed osteopenia in one or more of the total body, hip or spine scans. Mean urine-specific gravity (Usg) values revealed moderate dehydration on a non-race day (Usg = 1.022 +/- 0.005 and 1.021 +/- 0.007 for flat and national hunt jockeys respectively). Analysis of a number of flat jockeys (n = 11) revealed marked dehydration on an official race day (Usg = 1.028 +/- 0.005). Sixty-four percent of participants reported a current injury at the time of assessment. Our results reveal some worrying trends within this population. Further research is required to examine the effects of current weight control practices typically used by jockeys on both physiological and cognitive function as well as health and performance.