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1.
Artigo em Inglês | MEDLINE | ID: mdl-38791824

RESUMO

Down syndrome (DS) is characterised by a duplication of chromosome-21 and is linked to co-occurring physical and mental health conditions, including low self-efficacy and disturbed mood states. The purpose of this study was to investigate the effects of an eight-week prescribed physical and/or cognitive training intervention on measures of mood disturbance, life satisfaction and self-efficacy in a population of adults with DS. Eighty-three participants (age 27.1 ± 8.0 years) from across five continents volunteered. Participants were assigned using matched groups based upon performance in a modified six-minute walk test to either an exercise (EXE) 3 × 30 min of walking/jogging per week, cognitive training (COG) 6 × 20 min per week, a combined group (COM) or the control (CON) who did not complete any intervention. Profile of Mood States (POMS) were assessed using a five-point scale across 65 categories pre- and post-study as well as upon completion of each week of the intervention. In addition, Satisfaction with Life Scale (SWLS) and self-efficacy using the Generalised Self-Efficacy scale (GSE) were recorded before and after the intervention. GSE increased for all participants by 1.9 ± 5.2 (p = 0.002) from pre- to post-intervention, while POMS showed significant changes for the whole group from pre- to post-intervention for tension (p < 0.001), depression (p < 0.001) and for anger (p < 0.001). In addition, significant correlations were observed between SWLS and ΔTMD, Δtension, Δanger, and Δfatigue (p < 0.05) for EXE. Both COG and EXE provide a framework for empowering enhancements in life satisfaction, self-efficacy and mood states fostering improvements in quality of life.


Assuntos
Afeto , Síndrome de Down , Exercício Físico , Satisfação Pessoal , Autoeficácia , Humanos , Adulto , Masculino , Feminino , Adulto Jovem , Síndrome de Down/psicologia , Exercício Físico/psicologia , Cognição , Qualidade de Vida , Adolescente
2.
Artigo em Inglês | MEDLINE | ID: mdl-38063551

RESUMO

The duplication of chromosome 21, as evidenced in Down Syndrome (DS), has been linked to contraindications to health, such as chronotropic and respiratory incompetence, neuromuscular conditions, and impaired cognitive functioning. The purpose of this study was to examine the effects of eight weeks of prescribed exercise and/or cognitive training on the physical and cognitive health of adults with DS. Eighty-three participants (age 27.1 ± 8.0 years) across five continents participated. Physical fitness was assessed using a modified version of the six-minute walk test (6MWT), while cognitive and executive functions were assessed using the Corsi block test, the Sustained-Attention-To-Response Task (SART), and the Stroop task (STROOP). All were completed pre- and post-intervention. Participants were assigned to eight weeks of either exercise (EXE), 3 × 30 min of walking/jogging per week, cognitive training (COG) 6 × ~20 min per week, a combined group (COM), and a control group (CON) engaging in no intervention. 6MWT distance increased by 11.4% for EXE and 9.9% for COM (p < 0.05). For SART, there were positive significant interactions between the number of correct and incorrect responses from pre- to post-intervention when participants were asked to refrain from a response (NO-GO-trials) across all experimental groups (p < 0.05). There were positive significant interactions in the number of correct, incorrect, and timeout incompatible responses for STROOP in EXE, COG, and COM (p < 0.05). Walking generated a cognitive load attributed to heightened levels of vigilance and decision-making, suggesting that exercise should be adopted within the DS community to promote physical and cognitive well-being.


Assuntos
Síndrome de Down , Terapia por Exercício , Adulto , Humanos , Adulto Jovem , Síndrome de Down/terapia , Exercício Físico/psicologia , Cognição/fisiologia , Força Muscular/fisiologia
3.
Sports Health ; 14(5): 740-746, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35104417

RESUMO

BACKGROUND: Muscle weakness is common after injury in athletes and in the presence of hip pathology. It will cause abnormal hip biomechanics and can predict future injury. However, objective measurement of hip muscle strength is difficult to perform accurately and reliably. Therefore, it is challenging to determine when an athlete has returned to preinjury levels of strength. In addition, there is currently no standardized method of obtaining measurements, which prevents the data being compared or shared between research centers. PURPOSE: The purpose of this study is to comprehensively assess the inter- and intraobserver reliability of our standardized muscle strength measurement protocol. STUDY DESIGN: Descriptive laboratory study. LEVEL OF EVIDENCE: Level 3, inception cohort study. METHODS: A total of 16 healthy male volunteers (age = 28.3 ± 7.9 years) were recruited. Those with a previous history of hip injuries or disorders were excluded. These volunteers underwent strength testing according to the Cambridge Protocol on 4 separate occasions, performed by 2 independent assessors. Maximal voluntary contractions, fatigue torque fluctuations, and electromyography measurements were recorded. Intra- and interobserver reliability was assessed using intraclass correlation coefficient (ICC). RESULTS: Good-to-excellent correlation was seen for both intra- and interobserver reliability across almost all hip movements for maximal contractions: ICC ranged 0.78 to 0.93 and 0.78 to 0.96, respectively. The standard error of the mean for all hip movements was also extremely low at 2% to 3%. CONCLUSION: The Cambridge Protocol is a highly reliable method for objective measurement of hip muscle strength. We recommend future studies use this protocol, or the principles underpinning it, to enable data sharing and comparison across different studies. CLINICAL RELEVANCE: This is a description and analysis of hip muscle strength measurement. If widely used, it will allow for accurate and objective strength assessment and closer monitoring of hip injuries and pathology.


Assuntos
Lesões do Quadril , Força Muscular , Adulto , Estudos de Coortes , Eletromiografia , Humanos , Masculino , Força Muscular/fisiologia , Dinamômetro de Força Muscular , Músculo Esquelético/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem
4.
J Vis Impair Blind ; 116(6): 806-816, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38603412

RESUMO

Introduction: The introduction of the COVID-19 lockdown and social distancing policy has the potential to restrict access to physical activity, change exercise behavior, and to increase sedentary behavior. This study was conducted with the support of British Blind Sport and evaluates the effect of the lockdown policy on adults with visual impairments in the United Kingdom (UK). Methods: An online survey based on the World Health Organization's Global Physical Activity Questionnaire was completed by 73 participants (median age 35-44 years, 59% female) to gain information on how the implementation of the lockdown policy by the UK government has affected physical activity and sedentary behavior in adults that are visually impaired. Paired sample t-tests and Wilcoxon signed rank tests were used to analyze continuous and Likert scale data, respectively. Results: The majority of participants continued to exercise during lockdown, but the nature of this activity altered with a significant change to exercising in a private indoor space (+190% (always), z = -3.871, p < 0.001), and those exercising alone (+118% (always), z = -2.595, p = 0.009). The volume of activity reduced in all cases, between -11% and -52%, with significant changes in duration of vigorous day-to-day activity, moderate day-to-day activity, travel by foot or cycle, and vigorous recreational activity. Sedentary behavior increased on average by 21% (t(59) = -2.050, p = 0.045), with a greater effect seen in females (+36%, t(35) = -2.525, p = 0.016). Discussion: Reductions in physical activity volume and increases in sedentary behavior are consequences of the UK lockdown for those with visual impairments. The health and well-being implications of these data to this specific population are of particular concern. Implications for Practitioners: Lockdown measures should be designed with consideration of the needs of people with disabilities. Innovative ways to engage these populations in physical activity are strongly encouraged.

5.
J Int Soc Sports Nutr ; 17(1): 54, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33176826

RESUMO

BACKGROUND: Prevalence of vitamin D insufficiency/deficiency has been noted in athletic populations, although less is known about recreationally active individuals. Biofortification of natural food sources (e.g. UV radiated mushrooms) may support vitamin D status and is therefore of current scientific and commercial interest. The aim of this study was to assess the impact of a mushroom-derived food ingredient on vitamin D status in recreationally active, healthy volunteers. METHODS: Twenty-eight participants were randomly assigned to either: 25 µg (1000 IU) encapsulated natural mushroom-derived vitamin D2; matched-dose encapsulated vitamin D3 or placebo (PL) for 12 weeks. Venous blood samples were collected at baseline, week 6 and 12 for analysis of serum 25(OH)D2 and 25(OH)D3 using liquid chromatography mass spectrometry. Habitual dietary intake and activity were monitored across the intervention. RESULTS: Vitamin D status (25(OH)DTOTAL) was significantly increased with vitamin D3 supplementation from 46.1 ± 5.3 nmol·L- 1 to 88.0 ± 8.6 nmol·L- 1 (p < 0.0001) across the intervention, coupled with an expected rise in 25(OH)D3 concentrations from 38.8 ± 5.2 nmol·L- 1 to 82.0 ± 7.9 nmol·L- 1 (p < 0.0001). In contrast, D2 supplementation increased 25(OH)D2 by + 347% (7.0 ± 1.1 nmol·L- 1 to 31.4 ± 2.1 nmol·L- 1, p < 0.0001), but resulted in a - 42% reduction in 25(OH)D3 by week 6 (p = 0.001). A net + 14% increase in 25(OH)DTOTAL was established with D2 supplementation by week 12 (p > 0.05), which was not statistically different to D3. Vitamin D status was maintained with PL, following an initial - 15% reduction by week 6 (p ≤ 0.046 compared to both supplement groups). CONCLUSIONS: The use of a UV radiated mushroom food ingredient was effective in maintaining 25(OH)DTOTAL in healthy, recreationally active volunteers. This may offer an adjunct strategy in supporting vitamin D intake. However, consistent with the literature, the use of vitamin D3 supplementation likely offers benefits when acute elevation in vitamin D status is warranted.


Assuntos
25-Hidroxivitamina D 2/sangue , Agaricales/química , Calcifediol/sangue , Ergocalciferóis/administração & dosagem , Alimentos Fortificados , Adulto , Agaricales/efeitos da radiação , Colecalciferol/administração & dosagem , Colecalciferol/sangue , Dieta , Método Duplo-Cego , Ergocalciferóis/sangue , Humanos , Deficiência de Vitamina D/tratamento farmacológico
6.
J Sports Med Phys Fitness ; 60(1): 53-61, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32008311

RESUMO

BACKGROUND: Sprint interval training is a popular workout modality. Studies have eluded to a positive effect on maximal oxygen uptake, however little is known about the mechanistic basis of this adaptation. Therefore, the purpose of this study was to determine the effects of a short-term high-intensity sprint interval training (SIT) intervention on V̇O2max through quantification of both the respiratory and hemodynamic responses. METHODS: Thirty-six physically active participants undertook 4 weeks of either cycling-based SIT (8×20 s at 170% P-V̇O2max with 10 s recovery) or continuous exercise training (CET) (30 min at 70% P-V̇O2max) 3 times per week. V̇O2max, blood-based markers and hemodynamic responses were assessed pre and post the intervention period. V̇O2max was assessed using breath-by-breath open circuit spirometry, while hemodynamic responses were monitored using thoracic impedance cardiography. RESULTS: V̇O2max exhibited a non-significant 4.1% increase (ES=0.24) for SIT with 7.0% P=0.007 (ES=0.40) increase for CET. Hemodynamic responses (maximal cardiac output, maximal stroke volume) displayed non-significant responses for CET and SIT while a-vO2dif-max increased from 15.8±4.8 to 18.3±2.9 mL/100 mL) (P=0.02) (ES=0.63) in SIT. CONCLUSIONS: V̇O2max is a function of maximal cardiac output and a-vO2dif-max, so for a meaningful change to occur in cardiorespiratory fitness, there must be a concomitant increase in O2 delivery. This study demonstrates that a low volume SIT intervention evokes peripherally mediated responses (a-vO2dif) and anaerobic substrate utilization rather than O2 delivery components. Future works should address the time course of the responses and when assessing V̇O2max-based responses that due attention be given to the hemodynamic responses as means of quantification of the response.


Assuntos
Treinamento Intervalado de Alta Intensidade , Oxigênio/metabolismo , Adolescente , Adulto , Débito Cardíaco , Aptidão Cardiorrespiratória , Feminino , Coração/fisiologia , Hemodinâmica , Humanos , Masculino , Oxigênio/análise , Consumo de Oxigênio
8.
Clin Physiol Funct Imaging ; 38(4): 689-698, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28906053

RESUMO

The purpose of this study was to examine the effect of menstrual cycle phase on maximal oxygen uptake (V˙O2max) and associated cardiodynamic responses. A total of 16 active females volunteered of which n = 10 formed the non-oral contraceptive pill group (n-OCP), displaying a regular menstrual cycle of 28·4 ± 2·2 days (age 20·6 ± 1·6 years, height 169·9 ± 6·4 cm, mass 68·7 ± 7·9 kg) and n = 6 formed the oral contraceptive pill group (OCP) (monophasic pill) (age 21·7 years ± 2·16, height 168·1 cm ± 6·8 cm, mass 61·6 ± 6·8 kg). Each completed four incremental exercise tests for determination of V˙O2max, cardiac output, stroke volume and heart rate. Each test was completed according to the phases of the menstrual cycle as determined through salivary analysis of 17-ß oestrodiol and progesterone. Non-significant differences were observed for V˙O2max across phases and between groups (P>0·05) with additional non-significant differences for Q˙max, HRmax and SVmax between groups. For ∆ V˙O2 during the final 60 s of the V˙O2max trial, significant differences were observed between OCP and n-OCP (P<0·05) with OCP showing zero V˙O2 plateaus in three pseudo-phases. Significant difference observed for a-vO2dif n-OCP between premenstruation and menstruation at 30-100% V˙O2max (P<0·05). Data suggest that the V˙O2 -plateau is effected by monophasic oral contraceptive pill, furthermore these data imply that V˙O2max test outcome is independent of menstrual cycle phase but caution should be applied when evaluating maximal oxygen uptake in females who are administered a monophasic oral contraceptive pill.


Assuntos
Aptidão Cardiorrespiratória , Hemodinâmica , Ciclo Menstrual , Consumo de Oxigênio , Débito Cardíaco , Anticoncepcionais Orais Hormonais/administração & dosagem , Estradiol/sangue , Teste de Esforço , Feminino , Frequência Cardíaca , Hemodinâmica/efeitos dos fármacos , Humanos , Ciclo Menstrual/efeitos dos fármacos , Ciclo Menstrual/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Progesterona/metabolismo , Saliva/metabolismo , Fatores de Tempo , Adulto Jovem
9.
Nutrients ; 11(1)2018 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-30597865

RESUMO

Short-term energy deficit strategies are practiced by weight class and physique athletes, often involving high protein intakes to maximize satiety and maintain lean mass despite a paucity of research. This study compared the satiating effect of two protein diets on resistance-trained individuals during short-term energy deficit. Following ethical approval, 16 participants (age: 28 ± 2 years; height: 1.72 ± 0.03 m; body-mass: 88.83 ± 5.54 kg; body-fat: 21.85 ± 1.82%) were randomly assigned to 7-days moderate (PROMOD: 1.8 g·kg-1·d-1) or high protein (PROHIGH: 2.9 g·kg-1·d-1) matched calorie-deficit diets in a cross-over design. Daily satiety responses were recorded throughout interventions. Pre-post diet, plasma ghrelin and peptide tyrosine tyrosine (PYY), and satiety ratings were assessed in response to a protein-rich meal. Only perceived satisfaction was significantly greater following PROHIGH (67.29 ± 4.28 v 58.96 ± 4.51 mm, p = 0.04). Perceived cravings increased following PROMOD only (46.25 ± 4.96 to 57.60 ± 4.41 mm, p = 0.01). Absolute ghrelin concentration significantly reduced post-meal following PROMOD (972.8 ± 130.4 to 613.6 ± 114.3 pg·mL-1; p = 0.003), remaining lower than PROHIGH at 2 h (-0.40 ± 0.06 v -0.26 ± 0.06 pg·mL-1 normalized relative change; p = 0.015). Absolute PYY concentration increased to a similar extent post-meal (PROMOD: 84.9 ± 8.9 to 147.1 ± 11.9 pg·mL-1, PROHIGH: 100.6 ± 9.5 to 143.3 ± 12.0 pg·mL-1; p < 0.001), but expressed as relative change difference was significantly greater for PROMOD at 2 h (+0.39 ± 0.20 pg·mL-1 v -0.28 ± 0.12 pg·mL-1; p = 0.001). Perceived hunger, fullness and satisfaction post-meal were comparable between diets (p > 0.05). However, desire to eat remained significantly blunted for PROMOD (p = 0.048). PROHIGH does not confer additional satiating benefits in resistance-trained individuals during short-term energy deficit. Ghrelin and PYY responses to a test-meal support the contention that satiety was maintained following PROMOD, although athletes experiencing negative symptoms (i.e., cravings) may benefit from protein-rich meals as opposed to over-consumption of protein.


Assuntos
Dieta Rica em Proteínas , Ingestão de Energia , Metabolismo Energético , Treinamento Resistido , Resposta de Saciedade , Adulto , Feminino , Humanos , Masculino
10.
Open Access J Sports Med ; 8: 231-241, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29200895

RESUMO

PURPOSE: The aim of this study was to examine the physical and training characteristics of recreational marathon runners within finish time bandings (2.5-3 h, 3-3.5 h, 3.5-4 h, 4-4.5 h and >4.5 h). MATERIALS AND METHODS: A total of 97 recreational marathon runners (age 42.4 ± 9.9 years; mass 69.2 ± 11.3 kg; stature 172.8 ± 9.1 cm), with a marathon finish time of 229.1 ± 48.7 min, of whom n = 34 were female and n = 63 were male, completed an incremental treadmill test for the determination of lactate threshold (LT1), lactate turn point (LT2) and running economy (RE). Following a 7-min recovery, they completed a test to volitional exhaustion starting at LT2 for the assessment of [Formula: see text]. In addition, all participants completed a questionnaire gathering information on their current training regimes exploring weekly distances, training frequencies, types of sessions, longest run in a week, with estimations of training speed, and load and volume derived from these data. RESULTS: Training frequency was shown to be significantly greater for the 2.5-3 h group compared to the 3.5-4 h runners (P < 0.001) and >4.5 h group (P = 0.004), while distance per session (km·session-1) was significantly greater for the 2.5-3 h group (16.1 ± 4.2) compared to the 3.5-4 h group (15.5 ± 5.2; P = 0.01) and >4.5 h group (10.3 ± 2.6; P = 0.001). Race speed correlated with LT1 (r = 0.791), LT2 (r = 0.721) and distance per session (r = 0.563). CONCLUSION: The data highlight profound differences for key components of marathon running ([Formula: see text], LT1, LT2, RE and % [Formula: see text]) within a group of recreational runners with the discriminating training variables being training frequency and the absolute training speed.

11.
J Sports Sci Med ; 16(1): 105-111, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28344458

RESUMO

The purpose of this study was to examine the effects of non-contingent feedback in the form of heart rate (HR) on the incidence of plateau at V̇O2max. Ten physically active males (age 24.8 yrs ± 4.2; mass 81.4 ± 9.0 kg; stature 1.80 ± 0.11 m, V̇O2max 53.2 ± 5.8 ml·kg-1.min-1) who were V̇O2max testing naïve but were cognisant as to the heart rate responses to exercise completed four incremental tests to volitional exhaustion, separated by ~72 h for the determination of V̇O2max and gas exchange threshold. The first trial served as a familiarisation with the remaining three being experimental conditions where HR was presented in a screen projection as either the actual response (HR-A) or 10 b·min-1 higher than recorded (HR-H) or 10 b·min-1 lower (HR-L). Throughout all trials V̇O2 was recorded on a breath-by-breath basis with plateau criteria of ≤ 50 ml·min-1. RESULTS: A significant difference was observed for Δ V̇O2 over the final two consecutive 30s sampling periods between HR-A, both HR-L and HR-H (p = 0.049) and for the incidence of plateau response between condition (p = 0.021). An additional significant difference was observed for sub-maximal Δ V̇O2 responses between HR-A and HR-H (p = 0.049) and HR-A and HR-L (p = 0.006). Non-significant differences were observed for all other criteria. These data indicate that when presented with non-contingent feedback in the form of HR, that the perceptually orientated pacing schema becomes disrupted promoting a sparing of the finite anaerobic capacity to compensate for the imbalance between the afferent signal and perception of effort.

12.
Open Access J Sports Med ; 6: 249-57, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26346728

RESUMO

To assess pacing accuracy in a group of adolescent swimmers during an incremental step test. Fifteen well-trained swimmers (age 15±1.5 years; height 170.2±8.8 cm; mass 60.2±6.6 kg), completed two 7×200 m tests, separated by ~72 hours. They swam to a predetermined incrementally increasing pace per step and were instructed to swim at even pace. Upon completion of each step, rating of perceived exertion, heart rate and blood lactate were recorded. Significant differences observed for both trials between actual and predicted swim time (P<0.05). Significant differences also observed between the first and second 100 m of each step in trial 1 for step 1 (P=0.001, effect size [ES] =0.54), step 2 (P=0.0001, ES =0.57), step 4 (P=0.0001, ES =0.53), step 5 (P=0.005, ES =0.65), step 6 (P=0.0001, ES =0.50), and step 7 (P=0.0001, ES =0.70). Similar responses witnessed for trial 2 (P<0.05). Findings suggest that the finite anaerobic capacity was engaged sooner than would normally be anticipated, as a function of an inability to regulate pace. This is proposed to be a consequence of the volume of exposure to the biological and psychological sensations and cognitive developmental status. Given the apparent error in pacing judgment exhibited in this population group, caution should be applied when adopting such tests to monitor training responses with adolescent athletes, and alternate means of modulating pace be investigated.

13.
J Sports Sci Med ; 14(1): 47-53, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25729289

RESUMO

UNLABELLED: The purpose of this study was to assess the VO2max plateau response at VO2max during a series of pre-determined trials. METHODS: Ten male well-trained athletes (age, 23.0 ± 3.2; height, 183.3 ± 5.5 cm; mass 77.5 ± 11.1 Kg; VO2max 66.5 ± 5.0 ml(.)kg(-1,)min(-1)), but who were VO2max testing naïve and with prior-knowledge of trial number completed four incremental tests to volitional exhaustion, separated by ~72-h for the determination of VO2max and gas exchange threshold. Throughout all trials VO2max was recorded on a breath-by-breath basis using a pre-calibrated metabolic cart, using a plateau criterion of Δ VO2 ≤1.5 ml(.)kg(-1.)min(-1) over the final 2 consecutive 30 s sampling periods. A significant difference was observed between trial-1 and trial-4 for plateau incidence (p = 0.0285) rising from 20% in trial-1 to a 70% response rate in trial-4. Furthermore a significant difference was observed for VO2dif (difference between criterion value and Δ VO2) in trial-1, 1.02 ± 1.69 ml(.)kg(-1.)min(-1) (p = 0.038), with non-significant differences observed for all other trials, despite a non-significant difference for VO2max across all trials (p > 0.05). Finally, a significant difference was observed for effort perception (RPE) at volitional exhaustion between trial-1 (17.7 ± 1.3) and trial-4 (19.0 ± 1.4) (p = 0.0052). These data indicate that prior-knowledge of trial number can influence the manifestation of the VO2 plateau in a group of well-trained male athletes, thereby suggesting that a form of effort control is established in order to preserve the finite anaerobic capacity. Key pointsIn well-trained athletes the incidence of plateau at VO2max increases in conjunction with an increase in trial number and the associated sensations of pain and fatigue.By informing the participant of the number of trials to be completed a closed-loop condition is developed whereby effort in all trials is compared to a perceptually developed template.Closed-loop condition leads to a sparing of the finite anaerobic capacity during incremental tests when the number of trials to be completed is known.

14.
Eur J Appl Physiol ; 114(1): 21-7, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24122116

RESUMO

PURPOSE: The purpose of this study was to examine the effects of reductions in blood volume and associated oxygen-carrying capacity on the incidence of plateau at VO2max. METHODS: Fifteen well-trained athletes (age 23.3 ± 4.5; mass 77.4 ± 13.1 kg, height 180.1 ± 6.0 cm) completed three incremental cycle tests to volitional exhaustion, of which the first was defined as familiarisation, with the remaining two trials forming the experimental conditions of pre- (UBL) and post-(BLE) blood donation (~ 450 cm(3)). The work rate for the incremental tests commenced at 100 W for 60 s followed by a ramp of 0.42 W s(-1), with cadence being held constant at 80 rpm. Throughout all trials, VO2 was determined on a breath-by-breath basis using a pre-calibrated metabolic cart. The criteria for plateau determination was a ∆VO2 ≤ 50 ml min(-1) over the final two consecutive 30 s sampling periods. RESULTS: Despite a significant (P = 0.0028) 9.4 % reduction in haemoglobin concentration and 10.8 % (P = 0.016) reduction in erythrocyte count between UBL and BLE, there was no change in plateau incidence. However, significant differences were observed for both VO2max (P = 0.0059) 51.3 ± 7.6 (UBL) 48.4 ± 7.9 ml kg(-1) min(-1) (BLE) and gas exchange threshold arrival time 383.4 ± 85.2 s (UBL) 349.2 ± 71.4 s (BLE) (P = 0.0028). CONCLUSION: These data suggest that plateau at VO2max is unaffected by O2 availability lending support to the notion of the plateau being dependent on the anaerobic capacity and the classically orientated concept of VO2max.


Assuntos
Limiar Anaeróbio , Doadores de Sangue , Volume Sanguíneo , Adulto , Exercício Físico , Humanos , Masculino
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