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Stephen A. Ingham, Barry W. Fudge, Jamie S. Pringle and Andrew M. Jones

Prior high-intensity exercise increases the oxidative energy contribution to subsequent exercise and may enhance exercise tolerance. The potential impact of a high-intensity warm-up on competitive performance, however, has not been investigated.

Purpose:

To test the hypothesis that a high-intensity warm-up would speed VO2 kinetics and enhance 800-m running performance in well-trained athletes.

Methods:

Eleven highly trained middle-distance runners completed two 800-m time trials on separate days on an indoor track, preceded by 2 different warm-up procedures. The 800-m time trials were preceded by a 10-min self-paced jog and standardized mobility drills, followed by either 6 × 50-m strides (control [CON]) or 2 × 50-m strides and a continuous high-intensity 200-m run (HWU) at race pace. Blood [La] was measured before the time trials, and VO2 was measured breath by breath throughout exercise.

Results:

800-m time-trial performance was significantly faster after HWU (124.5 ± 8.3 vs CON, 125.7 ± 8.7 s, P < .05). Blood [La] was greater after HWU (3.6 ± 1.9 vs CON, 1.7 ± 0.8 mM; P < .01). The mean response time for VO2 was not different between conditions (HWU, 27 ± 6 vs CON, 28 ± 7 s), but total O2 consumed (HWU, 119 ± 18 vs CON, 109 ± 28 ml/kg, P = .05) and peak VO2 attained (HWU, 4.21 ± 0.85 vs CON, 3.91 ± 0.63 L/min; P = .08) tended to be greater after HWU.

Conclusions:

These data indicate that a sustained high-intensity warm-up enhances 800-m time-trial performance in trained athletes.

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Jason D. Vescovi and Jaci L. VanHeest

This observational case study examined the association of inter- and intraday energy intake and exercise energy expenditure with bone health, menstrual status and hematological factors in a female triathlete. The study spanned 7 months whereby energy intake and exercise energy expenditure were monitored three times (13 d); 16 blood samples were taken, urinary hormones were assessed for 3 months, and bone mineral density was measured twice. Energy availability tended to be sustained below 30 kcal/kg FFM/d and intraday energy intake patterns were often “back-loaded” with approximately 46% of energy consumed after 6 p.m. Most triiodothyronine values were low (1.1–1.2nmol/L) and supportive of reduced energy availability. The athlete had suppressed estradiol (105.1 ± 71.7pmol/L) and progesterone (1.79 ±1.19nmol/L) concentrations as well as urinary sex-steroid metabolites during the entire monitoring period. Lumbar spine (L1-L4) bone mineral density was low (age-matched Z-score −1.4 to −1.5). Despite these health related maladies the athlete was able to perform typical weekly training loads (swim: 30–40 km, bike: 120–300 km, run 45–70 km) and was competitive as indicated by her continued improvement in ITU World Ranking during and beyond the assessment period. There is a delicate balance between health and performance that can become blurred especially for endurance athletes. Education (athletes, coaches, parents) and continued monitoring of specific indicators will enable evidence-based recommendations to be provided and help reduced the risk of health related issues while maximizing performance gains. Future research needs to longitudinally examine how performance on standardized tests in each discipline (e.g., 800-m swim, 20-km time trial, 5-km run) is impacted when aspects of the female athlete triad are present.

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Shane Malone, Mark Roe, Dominic A. Doran, Tim J. Gabbett and Kieran D. Collins

Purpose:

To examine the association between combined session rating of perceived exertion (RPE) workload measures and injury risk in elite Gaelic footballers.

Methods:

Thirty-seven elite Gaelic footballers (mean ± SD age 24.2 ± 2.9 y) from 1 elite squad were involved in a single-season study. Weekly workload (session RPE multiplied by duration) and all time-loss injuries (including subsequent-wk injuries) were recorded during the period. Rolling weekly sums and wk-to-wk changes in workload were measured, enabling the calculation of the acute:chronic workload ratio by dividing acute workload (ie, 1-weekly workload) by chronic workload (ie, rolling-average 4-weekly workload). Workload measures were then modeled against data for all injuries sustained using a logistic-regression model. Odds ratios (ORs) were reported against a reference group.

Results:

High 1-weekly workloads (≥2770 arbitrary units [AU], OR = 1.63–6.75) were associated with significantly higher risk of injury than in a low-training-load reference group (<1250 AU). When exposed to spikes in workload (acute:chronic workload ratio >1.5), players with 1 y experience had a higher risk of injury (OR = 2.22) and players with 2–3 (OR = 0.20) and 4–6 y (OR = 0.24) of experience had a lower risk of injury. Players with poorer aerobic fitness (estimated from a 1-km time trial) had a higher injury risk than those with higher aerobic fitness (OR = 1.50–2.50). An acute:chronic workload ratio of (≥2.0) demonstrated the greatest risk of injury.

Conclusions:

These findings highlight an increased risk of injury for elite Gaelic football players with high (>2.0) acute:chronic workload ratios and high weekly workloads. A high aerobic capacity and playing experience appears to offer injury protection against rapid changes in workload and high acute:chronic workload ratios. Moderate workloads, coupled with moderate to high changes in the acute:chronic workload ratio, appear to be protective for Gaelic football players.

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Katrien De Bock, Bert O. Eijnde, Monique Ramaekers and Peter Hespel

Purpose:

The purpose of this study was to investigate the effect of acute and 4-week Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time, and attention.

Methods:

PHASE I: A double blind placebo-controlled randomized study (n = 24) was performed, consisting of 2 sessions (2 days per session). Day 1: One hour after acute Rhodiola rosea intake (R, 200-mg Rhodiola rosea extract containing 3% rosavin + 1% salidroside plus 500 mg starch) or placebo (P, 700 mg starch) speed of limb movement (plate tapping test), aural and visual reaction time, and the ability to sustain attention (Fepsy Vigilance test) were assessed. Day 2: Following the same intake procedure as on day 1, maximal isometric knee-extension torque and endurance exercise capacity were tested. Following a 5-day washout period, the experimental procedure was repeated, with the treatment regimens being switched between groups (session 2). PHASE II: A double blind placebo-controlled study (n = 12) was performed. Subjects underwent sessions 3 and 4, identical to Phase I, separated by a 4-week R/P intake, during which subjects ingested 200 mg R/P per day.

Results:

PHASE I: Compared with P, acute R intake in Phase I increased 0 < -05) time to exhaustion from 16.8 ± 0.7 min to 17.2 ± 0.8 min. Accordingly, VO2peak (p < .05) and VCO2peak(p< .05) increased during R compared to P from 50.9 ± 1.8 ml • min-1 • kg−1 to 52.9 ± 2.7 ml • min-1 • kg"’ (VO2peak) and from 60.0 ± 2.3 ml • min-1 • kg-’ to 63.5 ± 2.7 ml • min-1 kg-1 (VCO2peak). Pulmonary ventilation (p = .07) tended to increase more during R than during P(P: 115.9±7.7L/min; R: 124.8 ± 7.7 L/min). All other parameters remained unchanged. PHASE II: Four-week R intake did not alter any of the variables measured.

Conclusion:

Acute Rhodiola rosea intake can improve endurance exercise capacity in young healthy volunteers. This response was not altered by prior daily 4-week Rhodiola intake.

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360 360 10.1123/ijsn.9.4.345 Influence of Caffeine on Metabolic and Cardiovascular Functions during Sustained Light Intensity Cycling and at Rest Hermann-J. Engels * John C. Wirth * Sueda Celik * Jodee L. Dorsey * 12 1999 9 9 4 4 361 361 370 370 10.1123/ijsn.9.4.361 Ginseng Treatment Improves

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Naroa Etxebarria, Megan L. Ross, Brad Clark and Louise M. Burke

tract to these ingredients. 1 This new area of sport nutrition, typically known as “mouth rinsing,” emerged from observations of the performance benefits of carbohydrate (CHO) intake during shorter (∼1 h) protocols of sustained higher-intensity exercise. During these shorter protocols, CHO was unlikely

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Theo Ouvrard, Alain Groslambert and Frederic Grappe

, cyclists must sustain a mean PO ranging from 350 to 450 W for up to 60 minutes. 2 , 5 , 6 It is now well known that maintaining a high PO over a prolonged period of time involves a good regulation of exercise intensity throughout the event, generally called pacing strategy. 7 , 8 Results of the literature

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Mark Kramer, Mark Watson, Rosa Du Randt and Robert W. Pettitt

consequently introduced which represented the maximum work rate that could be sustained for prolonged periods without fatigue and was characterized by the asymptote of the power–time ( P – t ) relationship. 8 The P – t relationship also revealed an “energy store” parameter, termed W ′, which denoted a

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Kim Beals, Katherine A. Perlsweig, John E. Haubenstriker, Mita Lovalekar, Chris P. Beck, Darcie L. Yount, Matthew E. Darnell, Katelyn Allison and Bradley C. Nindl

food/fluids to support the high demand of operational training in the cold. Combining sustained training missions with challenging environmental conditions and inadequate fueling may exacerbate physiological and musculoskeletal stress and predispose students to early onset fatigue and injury. Energy

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Rachael L. Thurecht and Fiona E. Pelly

values and beliefs If the food aligns with my values for animal welfare (i.e., no animal products/vegan, cruelty-free raised animals) −0.02 0.01 0.06 −0.14 −0.19 0.05 0.79 −0.02 −0.13 0.71 My religious food beliefs −0.03 0.04 −0.01 0.06 0.20 −0.01 0.79 −0.21 0.08 0.72 If the food is sustainably produced