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Daniel Muniz-Pumares, Charles Pedlar, Richard J. Godfrey and Mark Glaister

Purpose:

The aim of the study was to determine the effect of supramaximal exercise intensity during constant work-rate cycling to exhaustion on the accumulated oxygen deficit (AOD) and to determine the test–retest reliability of AOD.

Methods:

Twenty-one trained male cyclists and triathletes (mean ± SD for age and maximal oxygen uptake [V̇O2max] were 41 ± 7 y and 4.53 ± 0.54 L/min, respectively) performed initial tests to determine the linear relationship between V̇O2 and power output, and V̇O2max. In subsequent trials, AOD was determined from exhaustive square-wave cycling trials at 105%, 112.5% (in duplicate), 120%, and 127.5% V̇O2max.

Results:

Exercise intensity had an effect (P = .011) on the AOD (3.84 ± 1.11, 4.23 ± 0.96, 4.09 ± 0.87, and 3.93 ± 0.89 L at 105%, 112.5%, 120%, and 127.5% V̇O2max, respectively). Specifically, AOD at 112.5% V̇O2max was greater than at 105% V̇O2max (P = .033) and at 127.5% V̇O2max (P = .022), but there were no differences between the AOD at 112.5% and 120% V̇O2max. In 76% of the participants, the maximal AOD occurred at 112.5% or 120% V̇O2max. The reliability statistics of the AOD at 112.5% V̇O2max, determined as intraclass correlation coefficient and coefficient of variation, were .927 and 8.72%, respectively.

Conclusions:

The AOD, determined from square-wave cycling bouts to exhaustion, peaks at intensities of 112.5–120% V̇O2max. Moreover, the AOD at 112.5% V̇O2max exhibits an 8.72% test–retest reliability.

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Charles R. Pedlar, Gregory P. Whyte, Richard Burden, Brian Moore, Gill Horgan and Noel Pollock

This case study examines the impact of low serum ferritin (sFe) on physiological assessment measures and performance in a young female 1500-m runner undertaking approximately 95–130 km/wk training. The study spans 4 race seasons and an Olympic Games. During this period, 25 venous blood samples were analyzed for sFe and hemoglobin (Hb); running economy, VO2max, and lactate threshold were measured on 6 occasions separated by 8–10 mo. Training was carefully monitored including 65 monitored treadmill training runs (targeting an intensity associated with the onset of blood lactate accumulation) using blood lactate and heart rate. Performances at competitive track events were recorded. All data were compared longitudinally. Mean sFe was 24.5 ± 7.6 μg/L (range 10–47), appearing to be in gradual decline with the exception of 2 data points (37 and 47 μg/L) after parenteral iron injections before championships, when the lowest values tended to occur, coinciding with peak training volumes. Each season, 1500-m performance improved, from 4:12.8 in year 1 to 4:03.5 in year 4. VO2max (69.8 ± 2.0 mL · kg−1 · min−1) and running economy (%VO2max at a fixed speed of 16 km/h; max 87.8%, min 80.3%) were stable across time and lactate threshold improved (from 14 to 15.5 km/h). Evidence of anemia (Hb <12 g/dL) was absent. These unique data demonstrate that in 1 endurance athlete, performance can continue to improve despite an apparent iron deficiency. Raising training volume may have caused increased iron utilization; however, the effect of this on performance is unknown. Iron injections were effective in raising sFe in the short term but did not appear to affect the long-term pattern.

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Nathan A. Lewis, Ann Redgrave, Mark Homer, Richard Burden, Wendy Martinson, Brian Moore and Charles R. Pedlar

Purpose: To examine a diagnosis of unexplained underperformance syndrome (UUPS, or overtraining syndrome) in an international rower describing a full recovery and return to elite competition the same year. Methods: On diagnosis and 4 and 14 mo postdiagnosis, detailed assessments including physiological, nutritional, and biomarkers were made. Results: Clinical examination and laboratory results for hematology, biochemistry, thyroid function, immunology, vitamins, and minerals were unremarkable and did not explain the presentation and diagnosis. Redox biomarkers including hydroperoxides, plasma antioxidant capacity, red blood cell glutathione, superoxide dismutase, coenzyme Q10, vitamin E (α- and γ-tocopherol), and carotenoids (lutein, α-carotene, β-carotene) provided evidence of altered redox homeostasis. The recovery strategy began with 12 d of training abstinence and nutritional interventions, followed by 6 wk of modified training. At 4 mo postintervention, performance had recovered strongly, resulting in the athlete’s becoming European champion that same year. Further improvements in physiological and performance indices were observed at 14 mo postintervention. Physiologically relevant increases in concentrations of carotenoids were achieved at each postintervention time point, exceeding the reported critical-difference values. Conclusions: Increasing athlete phytonutrient intake may enhance recovery and tolerance of training and environmental stressors, reducing the risk of unexplained UUPS. Alterations in redox homeostasis should be considered as part of the medical management in UUPS. This is the first reported case study of an elite athlete with alterations in redox homeostasis in conjunction with a diagnosis of UUPS.

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Jessica Hill, Glyn Howatson, Ken van Someren, David Gaze, Hayley Legg, Jack Lineham and Charles Pedlar

Compression garments are frequently used to facilitate recovery from strenuous exercise.

Purpose:

To identify the effects of 2 different grades of compression garment on recovery indices after strenuous exercise.

Methods:

Forty-five recreationally active participants (n = 26 male and n = 19 female) completed an eccentric-exercise protocol consisting of 100 drop jumps, after which they were matched for body mass and randomly but equally assigned to a high-compression pressure (HI) group, a low-compression pressure (LOW) group, or a sham ultrasound group (SHAM). Participants in the HI and LOW groups wore the garments for 72 h postexercise; participants in the SHAM group received a single treatment of 10-min sham ultrasound. Measures of perceived muscle soreness, maximal voluntary contraction (MVC), countermovement-jump height (CMJ), creatine kinase (CK), C-reactive protein (CRP), and myoglobin (Mb) were assessed before the exercise protocol and again at 1, 24, 48, and 72 h postexercise. Data were analyzed using a repeated-measures ANOVA.

Results:

Recovery of MVC and CMJ was significantly improved with the HI compression garment (P < .05). A significant time-by-treatment interaction was also observed for jump height at 24 h postexercise (P < .05). No significant differences were observed for parameters of soreness and plasma CK, CRP, and Mb.

Conclusions:

The pressures exerted by a compression garment affect recovery after exercise-induced muscle damage, with higher pressure improving recovery of muscle function.

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David J. Muggeridge, Christopher C. F. Howe, Owen Spendiff, Charles Pedlar, Philip E. James and Chris Easton

The aim of the current study was to determine the effects of dietary nitrate ingestion on parameters of submaximal and supramaximal exercise and time trial (TT) performance in trained kayakers. Eight male kayakers completed four exercise trials consisting of an initial discontinuous graded exercise test to exhaustion and three performance trials using a kayak ergometer. The performance trials were composed of 15 min of paddling at 60% of maximum work rate, five 10-s all-out sprints, and a 1 km TT. The second and third trials were preceded by ingestion of either 70 ml nitrate-rich concentrated beetroot juice (BR) or tomato juice (placebo [PLA]) 3 hr before exercise using a randomized crossover design. Plasma nitrate (PLA: 33.8 ± 1.9 μM, BR: 152 ± 3.5 μM) and nitrite (PLA: 519.8 ± 25.8, BR: 687.9 ± 20 nM) were higher following ingestion of BR compared with PLA (both p < .001). VO2 during steady-state exercise was lower in the BR trial than in the PLA trial (p = .010). There was no difference in either peak power in the sprints (p = .590) or TT performance between conditions (PLA: 277 ± 5 s, BR: 276 ± 5 s, p = .539). Despite a reduction in VO2, BR ingestion appears to have no effect on repeated supramaximal sprint or 1 km TT kayaking performance. A smaller elevation in plasma nitrite following a single dose of nitrate and the individual variability in this response may partly account for these findings.

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Noel Pollock, Claire Grogan, Mark Perry, Charles Pedlar, Karl Cooke, Dylan Morrissey and Lygeri Dimitriou

Low bone-mineral density (BMD) is associated with menstrual dysfunction and negative energy balance in the female athlete triad. This study determines BMD in elite female endurance runners and the associations between BMD, menstrual status, disordered eating, and training volume. Forty-four elite endurance runners participated in the cross-sectional study, and 7 provided longitudinal data. Low BMD was noted in 34.2% of the athletes at the lumbar spine, and osteoporosis in 33% at the radius. In cross-sectional analysis, there were no significant relationships between BMD and the possible associations. Menstrual dysfunction, disordered eating, and low BMD were coexistent in 15.9% of athletes. Longitudinal analysis identified a positive association between the BMD reduction at the lumbar spine and training volume (p = .026). This study confirms the presence of aspects of the female athlete triad in elite female endurance athletes and notes a substantial prevalence of low BMD and osteoporosis. Normal menstrual status was not significantly associated with normal BMD, and it is the authors’ practice that all elite female endurance athletes undergo dual-X-ray absorptiometry screening. The association between increased training volume, trend for menstrual dysfunction, and increased loss of lumbar BMD may support the concept that negative energy balance contributes to bone loss in athletes.

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Nathan A. Lewis, Andrew J. Simpkin, Sarah Moseley, Gareth Turner, Mark Homer, Ann Redgrave, Charles R. Pedlar and Richard Burden

Background: Identifying strategies that reduce the risk of illness and injury is an objective of sports science and medicine teams. No studies have examined the relationship between oxidative stress (OS) and illness or injury in international athletes undergoing periods of intensified training and competition. Purpose: The authors aimed to identify relationships between illness, injury, and OS. Methods: A longitudinal, observational study of elite male rowers (n = 10) was conducted over 18 weeks, leading into World Championships. Following a recovery day and a 12-hour fast, hydroperoxides (free oxygen radicals test) and total antioxidant capacity (free oxygen radicals defense) were measured in venous blood, with the ratio calculated as the oxidative stress index (OSI). At all study time points, athletes were independently dichotomized as ill or not ill, injured or not injured. OS data were compared between groups using independent t tests. A Cox proportional hazard model was used to assess the association of OS with injury and illness while adjusting for age and body mass index. Results: Free oxygen radicals defense was lower (P < .02) and OSI was higher (P < .001) with illness than without illness. Free oxygen radicals test and OSI were higher with injury than without injury (P < .001). A 0.5 mmol·L−1 increase in free oxygen radicals defense was associated with a 30.6% illness risk reduction (95% confidence interval, 7%–48%, P = .014), whereas 0.5 unit increase in OSI was related to a 11.3% increased illness risk (95% confidence interval, 1%–23%, P = .036). Conclusions: OS is increased in injured and ill athletes. Monitoring OS may be advantageous in assessing recovery from and in reducing injury and illness risk given the association.