• The effect of acute hypoxia on heat shock protein 72 expression and oxidative stress in vivo

      Taylor, Lee; Midgley, Adrian W.; Chrismas, Bryna C.; Madden, Leigh A.; Vince, Rebecca V.; McNaughton, Lars R. (Springer, 2010)
      The inducible human stress protein HSP72 performs vital roles within the body at rest and during periods of stress. Recently, a previously disclosed quadratic trend in basal HSP72 expression was shown to be reliable and repeatable. The notion of a physiological stressor such as hypoxia disrupting this basal quadratic trend is an interesting one. Monocyte-expressed HSP72 and TBARS were determined every 3 h, over a 12-h period in 12 healthy male subjects on two separate days, with trial day one ascertaining control values. A hypoxic intervention consisting of 75 min at a simulated altitude of 2,980 m, commencing and ceasing at 0930 and 1045, respectively, was incorporated on trail day 2. The hypoxic condition induced significantly (elevated) HSP72 values at 1100 (P = 0.002), 1400 (P < 0.001), 1700 (P = 0.034) and 2000 (P = 0.041) compared to control. Significant increases in plasma TBARS were seen in the hypoxic condition compared to control at 1100 (P = 0.006) and 1400 (P = 0.032). The results demonstrate that a 75-min bout of normobaric hypoxia is sufficient to induce significant increases in HSP72 expression, which disrupts the basal quadratic trend shown by others and here in the control condition. This increase may be linked to the observed changes in oxidative stress. These results may provide a tool for manipulating basal monocyte HSP72 expression within human heat acclimation exercise protocols.
    • Effect of breakfast glycemic index on metabolic responses during rest and exercise in overweight and non-overweight adolescent girls

      Zakrzewski-Fruer, Julia K.; Stevenson, E.J.; Tolfrey, Keith (Nature Publishing Group, 2011)
      The metabolic responses to mixed breakfast meals with different glycemic indexes (GI) and their effects on substrate metabolism during exercise in adolescent girls have not been examined. The interaction with weight status also warrants investigation. This study investigated the effect of mixed breakfast meals containing high GI (HGI) or low GI (LGI) carbohydrates on metabolic responses and fat oxidation during rest and exercise in overweight (OW) and non-overweight (NO) adolescent girls.
    • The effect of different dynamic stretch velocities on jump performance.

      Fletcher, Iain M.; University of Bedfordshire (2010-06)
      Dynamic stretching has gained popularity, due to a number of studies showing an increase in high intensity performance compared to static stretch modalities. Twenty-four males (age mean 21 +/- 0.3 years) performed a standardised 10 min jogging warm-up followed by either; no stretching (NS), slow dynamic stretching at 50 b/min (SDS) or fast dynamic stretching at 100 b/min (FDS). Post-warm-up, squat, countermovement and depth jumps were performed. Heart rate, tympanic temperature, electromyography (EMG) and kinematic data (100 Hz) were collected during each jump. Results indicated that the FDS condition showed significantly greater jump height in all tests compared to the SDS and NS conditions. Further, the SDS trial resulted in significantly greater performance in the drop and squat jump compared to the NS condition. The reasons behind these performance changes are multi-faceted, but appear to be related to increases in heart rate and core temperature with slow dynamic stretches, while the greater increase in performance for the fast dynamic stretch intervention is linked to greater nervous system activation, shown by significant increases in EMG. In conclusion, a faster dynamic stretch component appears to prepare an athlete for a more optimum performance.
    • The effect of isokinetic testing speed on the reliability of muscle fatigue indicators during a hip abductor-adductor fatigue protocol

      Gautrey, Charlotte N.; Watson, T.; Mitchell, Andrew C.S. (Thieme Publishing, 2013)
      The aim of this study was to investigate the reliability of fatigue indicators calculated from peak torque and total work during isokinetic speeds of 60, 90, 120 and 180° · s-1 during a hip fatigue protocol.
    • The effect of short-term creatine loading on active range of movement

      Sculthorpe, Nicholas; Grace, Fergal; Jones, Peter; Fletcher, Iain M.; University of Bedfordshire (2010-08)
      During high-intensity exercise, intracellular creatine phosphate (PCr) is rapidly broken down to maintain adenosine triphosphate turnover. This has lead to the widespread use of creatine monohydrate as a nutritional ergogenic aid. However, the increase in intracellular PCr and the concomitant increase in intracellular water have not been investigated with regard to their effect on active range of movement (ROM). Forty male subjects (age, 24+/-3.2 years) underwent restricted randomization into 2 equal groups, either an intervention group (CS) or a control group (C). The CS group ingested 25 g.day(-1) of creatine monohydrate for 5 days, followed by 5 g.day(-1) for a further 3 days. Before (24 h before starting supplementation (PRE) and after (on the 8th day of supplementation (POST)) this loading phase, both groups underwent goniometry measurement of the shoulder, elbow, hip, and ankle. Data indicated significant reductions in active ROM in 3 movements: shoulder extension (57+/-11.3 degrees PRE vs. 48+/-11.2 degrees POST, p<0.01), shoulder abduction (183.4+/-6.8 degrees PRE vs. 180.3+/-5.1 degrees POST, p<0.05), and ankle dorsiflexion (14.2+/-4.7 degrees PRE vs. 12.1+/-6.4 degrees POST, p<0.01). There was also a significant increase in body mass for the CS group (83.6+/-6.2 kg vs. 85.2+/-6.3 kg, p<0.05). The results suggest that short-term supplementation with creatine monohydrate reduces the active ROM of shoulder extension and abduction and of ankle dorsiflexion. Although the mechanism for this is not fully understood, it may be related to the asymmetrical distribution of muscle mass around those joints.
    • The effect of the hyperbaric environment on heat shock protein 72 expression in vivo

      Taylor, Lee; Midgley, Adrian W.; Sandström, Marie E.; Chrismas, Bryna C.; McNaughton, Lars R. (Taylor and Francis, 2012-04)
      Heat shock protein 72 (HSP72) is expressed in response to stress and has been demonstrated to follow a diurnal expression pattern within monocytes and is sensitive to changes in core temperature. Numerous studies have shown changes in HSP72 expression within cell lines exposed to hyperbaric conditions. No studies have investigated changes in HSP72 expression in vivo. Six males participated in the study and were exposed to hyperbaric air and hyperbaric oxygen a week apart. Monocyte HSP72 was analyzed by flow cytometry at 09:00, 13:00, 17:00, 21:00 with hyperbaric oxygen or hyperbaric air breathing commencing at 15:00 for 78 min at a pressure of 2.8 ATA. HSP72 under normoxia followed the established trend; however, following the hyperbaric air or oxygen exposure a reduction in detectable HSP72 was observed at 17:00 and 21:00. No changes in core temperature were observed between 13:00 and 21:00 for any condition. The data show that HSP72 expression is impaired following hyperbaric air (HA) exposure, when compared with control or hyperbaric oxygen (HO) exposure.
    • The effect of velocity on load range during isokinetic hip abduction and adduction exercise

      Gautrey, Charlotte N.; Watson, T.; Mitchell, Andrew C.S. (Thieme Publishing, 2013)
      The purpose of this study was to quantify the components of acceleration, load range and deceleration through a velocity spectrum during concentric hip abduction and adduction isokinetic exercise, and to investigate the effect of load range on peak torque and work done.
    • Effective research writing

      Kirk, David; Casey, Ashley (Routledge, 2011)
    • The effectiveness of aligned developmental feedback on the overhand throw in third-grade students

      Cohen, Rona; Goodway, Jacqueline D.; Lidor, Ronnie (Taylor and Francis, 2012)
      To improve student performance, teachers need to evaluate the developmental level of the child and to deliver feedback statements that correspond with the student’s ability to process the information delivered. Therefore, feedback aligned with the developmental level of the child (aligned developmental feedback – ADF) is sometimes considered to be the most appropriate type of feedback for improving student learning. It is assumed that the provision of ADF is beneficial in bringing about improvement in the learning of motor skills and subsequently in performance. However, the extent of the influence of ADF on motor performance remains unclear. This study examined the influence of ADF on students’ performance of the overhand throw for force in a naturalistic physical education setting.
    • Effects of exercise intensity on salivary antimicrobial proteins and markers of stress in active men

      Allgrove, Judith E.; Gomes, Elisa; Hough, John; Gleeson, Michael; Loughborough University (Taylor & Francis, 2008-04)
      In the present study, we assessed the effects of exercise intensity on salivary immunoglobulin A (s-IgA) and salivary lysozyme (s-Lys) and examined how these responses were associated with salivary markers of adrenal activation. Using a randomized design, 10 healthy active men participated in three experimental cycling trials: 50% maximal oxygen uptake ([Vdot]O2max), 75%[Vdot]O2max, and an incremental test to exhaustion. The durations of the trials were the same as for a preliminary incremental test to exhaustion (22.3 min, s x = 0.8). Timed, unstimulated saliva samples were collected before exercise, immediately after exercise, and 1 h after exercise. In the incremental exhaustion trial, the secretion rates of both s-IgA and s-Lys were increased. An increase in s-Lys secretion rate was also observed at 75%[Vdot]O2max. No significant changes in saliva flow rate were observed in any trial. Cycling at 75%[Vdot]O2max and to exhaustion increased the secretion of α-amylase and chromogranin A immediately after exercise; higher cortisol values at 75%[Vdot]O2max and in the incremental exhaustion trial compared with 50%[Vdot]O2max were observed 1 h immediately after exercise only. These findings suggest that short-duration, high-intensity exercise increases the secretion rate of s-IgA and s-Lys despite no change in the saliva flow rate. These effects appear to be associated with changes in sympathetic activity and not the hypothalamic – pituitary – adrenal axis.
    • Effects of handgrip training with venous restriction on brachial artery vasodilation

      Credeur, Daniel P.; Hollis, Brandon C.; Welsch, Michael A.; Louisiana State University (Wolters Kluwer/ Lippincott Williams & Wilkins, 2010-07)
      Previous studies have shown that resistance training with restricted venous blood flow (Kaatsu) results in significant strength gains and muscle hypertrophy. However, few studies have examined the concurrent vascular responses following restrictive venous blood flow training protocols.
    • The effects of precompetition massage on the kinematic parameters of 20-m sprint performance

      Fletcher, Iain M.; University of Bedfordshire (2010-05)
      The purpose of this study was to investigate what effect precompetition massage has on short-term sprint performance. Twenty male collegiate games players, with a minimum training/playing background of 3 sessions per week, were assigned to a randomized, counter-balanced, repeated-measures designed experiment used to analyze 20-m sprints performance. Three discrete warm-up modalities, consisting of precompetition massage, a traditional warm-up, and a precompetition massage combined with a traditional warm-up were used. Massage consisted of fast, superficial techniques designed to stimulate the main muscle groups associated with sprint running. Twenty-meter sprint performance and core temperature were assessed post warm-up interventions. Kinematic differences between sprints were assessed through a 2-dimensional computerized motion analysis system (alpha level p
    • An elevation of resting metabolic rate with declining health in nonagenarians may be associated with decreased muscle mass and function in women and men, respectively.

      Kim, Sangkyu; Welsh, David A.; Ravussin, Eric; Welsch, Michael A.; Cherry, Katie E.; Myers, Leann; Jazwinski, S. Michal; Tulane University Health Sciences Center; Louisiana State University Health Sciences Center; Pennington Biomedical Research Center; et al. (Oxford University Press, 2014-06)
      Previously, we showed that FI34, a frailty index based on 34 health and function ability variables, is heritable and a reliable phenotypic indicator of healthy aging. We have now examined the relationship between major components of energy expenditure and the FI34 in participants of the Louisiana Healthy Aging Study. Resting metabolic rate was associated with FI34, even after adjustment for fat-free mass, fat mass, age, sex, thyroid hormones, and insulin-like growth factor 1 levels, in multiple regression analyses. In contrast, there was no association between total daily energy expenditure and FI34. Circulating creatine phosphokinase, a clinical marker of muscle damage, was also significantly associated with FI34. However, these associations of resting metabolic rate with FI34 were restricted to the oldest old (≥90 years) and absent in younger age groups. In oldest old men, the association of FI34 with creatine phosphokinase persisted, whereas in the oldest old women, only the association with resting metabolic rate pertained with the appearance of an effect of body size and composition. These results point toward an increasing metabolic burden for the maintenance of homeodynamics as health declines in nonagenarians, and this has implications for contraction of metabolic reserve that may potentially accelerate the path to disability.
    • Endothelial function and stress response after simulated dives to 18 msw breathing air or oxygen

      Madden, Leigh A.; Chrismas, Bryna C.; Mellor, Duane; Vince, Rebecca V.; Midgley, Adrian W.; McNaughton, Lars R.; Atkin, Stephen L.; Laden, Gerard; University of Hull (Aerospace Medical Association, 2010-01)
      Decompression sickness is caused by gas bubbles released upon decompression. These bubbles have the potential to occlude blood vessels and damage the vascular endothelium. The aim of this study was to quantify damage to the vascular endothelium resulting from decompression by measuring endothelial microparticles (MP) and endothelial function.
    • Estimation of abdominal fat compartments by bioelectrical impedance: the validity of the ViScan measurement system in comparison with MRI

      Thomas, E. Louise; Collins, Adam L.; McCarthy, John; Fitzpatrick, Julie; Durighel, Giuliana; Goldstone, Anthony P.; Bell, Jimmy D.; Imperial College, London; University of Surrey; University of Bedfordshire (Nature Publishing Group, 2010-05)
      Abdominal obesity, more specifically increased intra-abdominal adipose tissue, is strongly associated with increased risk of metabolic disease. Bioelectrical impedance analysis (BIA) has been proposed as a potential method of determining individual abdominal fat compartments in the form of the commercially available ViScan measurement system (Tanita Corporation), but it has yet to be independently validated. The objective of this study was to analyse the validity of the ViScan to assess adult abdominal adiposity across a range of body fatness.
    • Evidence of altered cardiac electrophysiology following prolonged androgenic anabolic steroid use.

      Sculthorpe, Nicholas; Grace, Fergal; Jones, Peter; Davies, Bruce; University of Bedfordshire (2010-12)
      The non-therapeutic use of androgenic anabolic steroids (AAS) is associated with sudden cardiac death. Despite this, there is no proposed mechanism by which this may occur. Signal-averaged ECG (SAECG) allows the assessment of cardiac electrical stability, reductions of which are a known risk factor for cardiac arrhythmias. The aim of the present study was to examine cardiac electrical stability using SAECG in a group (n = 15) of long-term AAS users (AAS use 21.3 ± 3.1 years) compared with a group (n = 15) of age-matched weight lifters (WL) and age-matched sedentary controls [C (n = 15)]. AS, WL and C underwent SAECG analysis at rest and following an acute bout of exercise to volitional exhaustion. SAECGs were analyzed using a 40 Hz filter and were averaged over 200 beats. Results indicate a non-significant trend for increased incidence of abnormal SAECG measures at rest in AS (P = 0.55). However, AS demonstrated a significantly higher incidence of abnormalities of SAECG following exercise than C or WL (P < 0.05). In conclusion, the higher incidence of abnormal SAECG measurements immediately post-exercise in the AAS group places them at a greater risk of sudden death. The present study provides a strong contraindication to the use of AAS.
    • Exercise protocols to estimate Fatmax and maximal fat oxidation in children

      Zakrzewski-Fruer, Julia K.; Tolfrey, Keith (Human Kinetics, 2011-02)
      Consensus on the exercise protocol used to measure Fatmax (exercise intensity corresponding to maximum fat oxidation (MFO)) in children has not been reached. The present study compared Fatmax estimated using the 3 min incremental cycling protocol (3-INC) and a protocol consisting of several 10 min constant work rate exercise bouts (10-CWR) in 26 prepubertal children. Group Fatmax values were the same for 3-INC and 10-CWR (55% VO2peak) and 95% limits of agreement (LoA) were ± 7% VO2peak. Group MFO values were similar between protocols, although 95% LoA were -94 to 113 mg·min-1. While 3-INC provides a valid estimation of Fatmax compared with 10-CWR, caution should be exercised when estimating MFO in prepubertal children.
    • Exercise-associated DNA methylation change in skeletal muscle and the importance of imprinted genes: a bioinformatics meta-analysis

      Brown, William Michael; University of Bedfordshire (BMJ Publishing Group Limited, 2015-03-30)
      BACKGROUND: Epigenetics is the study of processes-beyond DNA sequence alteration-producing heritable characteristics. For example, DNA methylation modifies gene expression without altering the nucleotide sequence. A well-studied DNA methylation-based phenomenon is genomic imprinting (ie, genotype-independent parent-of-origin effects). OBJECTIVE: We aimed to elucidate: (1) the effect of exercise on DNA methylation and (2) the role of imprinted genes in skeletal muscle gene networks (ie, gene group functional profiling analyses). DESIGN: Gene ontology (ie, gene product elucidation)/meta-analysis. DATA SOURCES: 26 skeletal muscle and 86 imprinted genes were subjected to g:Profiler ontology analysis. Meta-analysis assessed exercise-associated DNA methylation change. DATA EXTRACTION: g:Profiler found four muscle gene networks with imprinted loci. Meta-analysis identified 16 articles (387 genes/1580 individuals) associated with exercise. Age, method, sample size, sex and tissue variation could elevate effect size bias. DATA SYNTHESIS: Only skeletal muscle gene networks including imprinted genes were reported. Exercise-associated effect sizes were calculated by gene. Age, method, sample size, sex and tissue variation were moderators. RESULTS: Six imprinted loci (RB1, MEG3, UBE3A, PLAGL1, SGCE, INS) were important for muscle gene networks, while meta-analysis uncovered five exercise-associated imprinted loci (KCNQ1, MEG3, GRB10, L3MBTL1, PLAGL1). DNA methylation decreased with exercise (60% of loci). Exercise-associated DNA methylation change was stronger among older people (ie, age accounted for 30% of the variation). Among older people, genes exhibiting DNA methylation decreases were part of a microRNA-regulated gene network functioning to suppress cancer. CONCLUSIONS: Imprinted genes were identified in skeletal muscle gene networks and exercise-associated DNA methylation change. Exercise-associated DNA methylation modification could rewind the 'epigenetic clock' as we age. TRIAL REGISTRATION NUMBER: CRD42014009800.
    • Exercise-induced dehydration with and without environmental heat stress results in increased oxidative stress

      Hillman, Angela R.; Vince, Rebecca V.; Taylor, Lee; McNaughton, Lars R.; Mitchell, Nigel; Siegler, Jason C. (NRC Research Press, 2011)
      While in vitro work has revealed that dehydration and hyperthermia can elicit increased cellular and oxidative stress, in vivo research linking dehydration, hyperthermia, and oxidative stress is limited. The purpose of this study was to investigate the effects of exercise-induced dehydration with and without hyperthermia on oxidative stress. Seven healthy male, trained cyclists (power output (W) at lactate threshold (LT): 199 ± 19 W) completed 90 min of cycling exercise at 95% LT followed by a 5-km time trial (TT) in 4 trials: (i) euhydration in a warm environment (EU-W, control), (ii) dehydration in a warm environment (DE-W), (iii) euhydration in a thermoneutral environment (EU-T), and (iv) dehydration in a thermoneutral environment (DE-T) (W: 33.9 ± 0.9 °C; T: 23.0 ± 1.0 °C). Oxidized glutathione (GSSG) increased significantly postexercise in dehydration trials only (DE-W: p < 0.01, DE-T: p = 0.03), and while not significant, total glutathione (TGSH) and thiobarbituric acid reactive substances (TBARS) tended to increase postexercise in dehydration trials (p = 0.08 for both). Monocyte heat shock protein 72 (HSP72) concentration was increased (p = 0.01) while lymphocyte HSP32 concentration was decreased for all trials (p = 0.02). Exercise-induced dehydration led to an increase in GSSG concentration while maintenance of euhydration attenuated these increases regardless of environmental condition. Additionally, we found evidence of increased cellular stress (measured via HSP) during all trials independent of hydration status and environment. Finally, both 90-min and 5-km TT performances were reduced during only the DE-W trial, likely a result of combined cellular stress, hyperthermia, and dehydration. These findings highlight the importance of fluid consumption during exercise to attenuate thermal and oxidative stress during prolonged exercise in the heat.