• Beneficial postprandial lipaemic effects of interrupting sedentary time with high-intensity physical activity versus a continuous moderate-intensity physical activity bout: a randomised crossover trial

      Maylor, Benjamin D.; Zakrzewski-Fruer, Julia K.; Orton, Charlie J.; Bailey, Daniel Paul; University of Bedfordshire (Elsevier, 2018-05-31)
      Objectives To compare the postprandial cardiometabolic response to prolonged sitting, continuous moderate-intensity physical activity (PA) followed by prolonged sitting, and interrupting prolonged sitting with hourly high-intensity PA breaks. Design Three-condition randomised crossover trial. Methods Fourteen sedentary and inactive adults aged 29 ± 9 years took part in three, 8-h conditions: (1) prolonged sitting (SIT), (2) a continuous 30-min moderate-intensity PA bout followed by prolonged sitting (CONT-SIT), and (3) sitting interrupted hourly with 2 min 32 s high-intensity PA bouts (SIT-ACT). The treadmill PA in conditions 2 and 3 were matched for energy expenditure. Two standardised test meals were consumed during each condition. Incremental area under the curve (iAUC) for each 8-h condition was calculated for glucose, insulin, triglyceride, and high-density lipoprotein cholesterol (HDL-C) concentrations. Statistical analyses were completed using linear mixed models. Results Compared with SIT, SIT-ACT lowered triglyceride iAUC by 2.23 mmol/L ∙ 8 h (95% CI −4.33, −0.13) and raised HDL-C iAUC by 0.99 mmol/L ∙ 8 h (0.05, 1.93) (all p ≤ 0.038). There was no significant difference in triglyceride or HDL-C iAUC between CONT-SIT and SIT or SIT-ACT (p ≥ 0.211). There were no significant differences between conditions for glucose or insulin iAUC (p ≥ 0.504). Conclusions This study suggests that interrupting prolonged sitting with hourly high-intensity PA breaks acutely improves postprandial triglyceride and HDL-C concentrations compared with prolonged sitting, whereas a continuous moderate-intensity PA bout does not.
    • Does parental support moderate the effect of children's motivation and self-efficacy on physical activity and sedentary behaviour?

      Gillison, F.B.; Standage, M.; Cumming, S.P.; Zakrzewski-Fruer, Julia K.; Rouse, P.C.; Katzmarzyk, P.T.; University of Bath; Pennington Biomedical Research Centre (Elsevier, 2017-07-13)
      Objectives: 1) To test whether parental support moderates the direct effects of children's motivation and self-efficacy on objectively measured moderate-vigorous physical activity (MVPA) and sedentary time. 2) To explore differences in the relationships between boys and girls. Design: Cross-sectional observational study. Method: Data were collected from 430 9-11 year old UK children and their parents; parents selfreported on the support they provided to their children to be active (through providing transport, encouragement, watching, or taking part with their child), and children self-reported their motivation and self-efficacy towards exercise. MVPA and sedentary time were measured using accelerometers. Results: Both parent- and child-level factors were largely positively associated with children's MVPA and negatively related to sedentary time. There was no evidence of a moderation effect of parental support on MVPA or sedentary time in boys. Parental provision of transport moderated the effect of girls' motivation on week-day MVPA; more motivated girls were less active when transport was provided. Transport and exercising with one's child moderated the effect of motivation and self-efficacy on girls' sedentary time at weekends; more motivated girls, and those with higher self-efficacy were less sedentary when parents provided more frequent transportation or took part in physical activity with them. Conclusions: The results largely supported a model of the independent effects of parent and child determinants for moderate-to-vigorous physical activity, but there was evidence that some types of parent support can moderate sedentary time in girls. Further research is needed to explore the causal pathways between the observed cross-sectional results.
    • The effects of artificial surface temperature on mechanical properties and player kinematics during landing and acceleration

      Charalambous, Laura H.; von Lieres Und Wilkau, Hans Christian; Potthast, Wolfgang; Irwin, Gareth; University of Bedfordshire; Cardiff Metropolitan University; German Sport University Cologne (Elsevier, 2015-06-12)
      Artificial turf is considered a feasible global alternative to natural turf by many sports governing bodies. Consequently, its ability to provide a safe and consistent playing surface regardless of climate becomes essential. The aims of this study were to determine the effects of artificial surface temperature on: (1) mechanical properties of the turf and (2) the kinematics of a turf-sport related movement. Two identical artificial turf pitches were tested: one with a cold surface temperature (1.8°C-2.4°C) and one with a warm surface temperature (14.5°C-15.2°C). Mechanical testing was performed to measure the surface properties. Four amateur soccer players performed a hurdle jump to sprint acceleration movement, with data (contact time, step length and hip, knee and ankle kinematics) collected using CODASport (200 Hz).  = 0.002) of the initial step after the landing were significantly longer on the warm surface. In addition, significant range of motion and joint angular velocity differences were found. These findings highlight different demands placed on players due to the surface temperature and suggest a need for coaches, practitioners, and sports governing bodies to be aware of these differences. Background Methods Results Conclusion
    • Full gait cycle analysis of lower limb and trunk kinematics and muscle activations during walking in participants with and without ankle instability

      Northeast, Lynsey; Gautrey, Charlotte N.; Bottoms, Lindsay; Hughes, Gerwyn T.G.; Mitchell, Andrew C.S.; Greenhalgh, Andrew; University of Hertfordshire; University of San Francisco; University of Bedfordshire (Elsevier, 2018-06-07)
      Background: Chronic ankle instability (CAI) has previously been linked to altered lower limb kinematics and muscle activation characteristics during walking, though little research has been performed analysing the full time-series across the stance and swing phases of gait. Research question: The aim of this study was to compare trunk and lower limb kinematics and muscle activity between those with chronic ankle instability and healthy controls. Methods: Kinematics and muscle activity were measured in 18 (14 males, 4 females) healthy controls (age 22.4 ± 3.6 years, height 177.8 ± 7.6 cm, mass 70.4 ± 11.9 kg, UK shoe size 8.4 ± 1.6), and 18 (13 males, 5 females) participants with chronic ankle instability (age 22.0 ± 2.7 years, height 176.8 ± 7.9 cm, mass 74.1 ± 9.6 kg, UK shoe size 8.1 ± 1.9) during barefoot walking trials, using a combined Helen Hayes and Oxford foot model. Surface electromyography (sEMG) was recorded for the tibialis anterior and gluteus medius. Full curve statistical parametric mapping was performed using independent and paired-samples T-tests. Results: No significant differences were observed in kinematic or sEMG variables between or within groups for the duration of the swing phase of gait. A significantly increased forefoot-tibia inversion was seen in the CAI affected limb when compared to the CAI unaffected limb at 4-16% stance (p = 0.039). No other significant differences were observed. Significance: There appears to be no differences in muscle activation and movement between CAI and healthy control groups. However, participants with CAI exhibited increased inversion patterns during the stance phase of gait in their affected limb compared to their unaffected limb. This may predispose those with CAI to episodes of giving way and further ankle sprains.
    • High intensity interval training (HIIT) improves resting blood pressure, metabolic (MET) capacity and heart rate reserve without compromising cardiac function in sedentary aging men

      Grace, Fergal; Herbert, Peter; Elliot, Adrian D.; Richards, Joanna C.; Beaumont, Alexander; Sculthorpe, Nicholas; Federation University; University of Wales Trinity Saint David; University of Adelaide; University of Bedfordshire; et al. (Elsevier, 2017-05-13)
      Background: This study examined a programme of pre-conditioning exercise with subsequent high intensity interval training (HIIT) on blood pressure, echocardiography, cardiac strain mechanics and maximal metabolic (MET) capacity in sedentary (SED) aging men compared with age matched masters athletes (LEX). Methods: Using a STROBE compliant observational design, 39 aging male participants (SED; n=22, aged 62.7± 5.2 yrs) (LEX; n = 17, aged= 61.1 ± 5.4 yrs) were recruited to a study that necessitated three distinct assessment phases; enrolment (Phase A), following pre-conditioning exercise in SED (Phase B), then following 6 weeks of HIIT performed once every five days by both groups before reassessment (Phase C). Hemodynamic, echocardiographic and cardiac strain mechanics were obtained at rest and maximal cardiorespiratory and chronotropic responses were obtained at each measurement phase. Results: The training intervention improved systolic, mean arterial blood pressure, rate pressure product and heart rate reserve (each P b 0.05) in SED and increased MET capacity in both SED and LEX (P b 0.01) which was amplified by HIIT. Echocardiography and cardiac strain measures were unremarkable apart from trivial increase to intra-ventricular septum diastole (IVSd) (P b 0.05) and decrease to left ventricular internal dimension diastole (LVId) (P b 0.05) in LEX following HIIT. Conclusions: A programme of preconditioning exercise with HIIT induces clinically relevant improvements in blood pressure, rate pressure product and encourages recovery of heart rate reserve in SED, while improving maximal MET capacity in both SED and LEX without inducing any pathological cardiovascular remodeling. These data add to the emerging repute of HIIT as a safe and promising exercise prescription to improve cardiovascular function and metabolic capacity in sedentary aging.
    • Polymorphonuclear leucocyte phagocytic function, γδ T-lymphocytes and testosterone as separate stress-responsive markers of prolonged, high-intensity training programs

      Leal, Diogo Luis Campos Vaz; Standing, Ariane S.I.; Furmanski, Anna L.; Hough, John; University of Bedfordshire; University Institute of Maia; University of Florida; Nottingham Trent University (Elsevier, 2021-03-06)
      Excessive exercise with limited recovery may lead to detrimental states of overreaching or the overtraining syndrome. Chronic maladaptation in endocrine and immune mechanisms occur with the incidence of these states. Exercise-induced cortisol and testosterone responses have been proposed as biomarkers of overreaching, with blunted responses following intensified-training periods. Yet, limited information on the effects of overreaching in immunity is available. Healthy individuals completed a 30-min running protocol (the RPETP) before and after a 12-day intensified-training period. Blood and saliva were collected before, after and 30min after RPETP at pre-training and post-training. Plasma and salivary cortisol and testosterone, leucocyte proliferation and polymorphonuclear leucocyte phagocytic activity were examined. Plasma and salivary cortisol were acutely unaffected pre-training (−14% and 0%, p > 0.05) and post-training (−14% and +46%, p > 0.05). Comparing pre-training with post-training, blunted responses were observed in plasma testosterone (43%–19%, p < 0.05) and salivary testosterone (55%–24%, p > 0.05). No acute or resting changes in total leucocyte counts or most leucocyte subsets occurred pre-training or post-training. Yet, a 194% acute elevation in γδ T-lymphocyte number occurred pre-training (p < 0.05), and average resting concentrations were 174% higher post-training. Baseline phagocytic activity was 47% lower post-training (p < 0.05). Intensified training was detrimental, significantly reducing phagocytic activity. Testosterone blunted post-training, indicating an excessive training-related hypothalamic-pituitary gonadal dysfunction. The γδ T-lymphocytes sensitivity to exercise was noted, rendering it as a potential stress-responsive cellular marker. The usefulness of the RPETP to track the onset of overreaching is proposed.
    • Sitting time and risk of cardiovascular disease and diabetes: a systematic review and meta-analysis

      Bailey, Daniel Paul; Hewson, David; Champion, Rachael B.; Sayegh, Suzan M.; University of Bedfordshire (Elsevier, 2019-08-01)
      Context: Whether physical activity attenuates the association of total daily sitting time with cardiovascular disease (CVD) and diabetes incidence is unclear. This systematic review and meta-analysis examined the association of total daily sitting time with CVD and diabetes with and without adjustment for physical activity. Evidence Acquisition: PubMed, Web of Science, BASE, MEDLINE, Academic Search Elite and ScienceDirect were searched for prospective studies published between 1st January 1989 and 15th February 2019 examining the association of total daily sitting time with CVD or diabetes outcomes. Data extraction and  study quality assessments were conducted by two independent reviewers. Pooled Hazard Ratios (HRs) were calculated using a fixed-effects model. The quality assessment and meta-analytic procedures were completed in 2018. Evidence Synthesis: Nine studies with 448,285 40 participants were included. Higher total daily sitting time was associated with a significantly increased risk of CVD (HR 1.29; 95%CI 1.27-1.30, p=<0.001) and diabetes (HR 1.13; 95%CI 1.04-1.22, p=<0.001) incidence when physical activity was not adjusted for. The increased risk for diabetes was unaffected when adjusting for physical activity (HR 1.11;  95%CI 1.01-1.19, p=<0.001). For CVD, the increased risk was attenuated but remained significant (HR 1.14; 95%CI 1.04-1.23, p=<0.001). Conclusions: Higher levels of total daily sitting time are associated with an increased risk of CVD and diabetes, independent of physical activity. Reductions in total daily sitting may thus be recommended in public health guidelines.
    • Sprint-based exercise and cognitive function in adolescents.

      Cooper, Simon B.; Bandelow, Stephan; Nute, Maria L.; Dring, Karah J.; Stannard, Rebecca L.; Morris, John G.; Nevill, Mary E.; University of Bedfordshire; Loughborough University (Elsevier, 2016-06-07)
      Moderate intensity exercise has been shown to enhance cognition in an adolescent population, yet the effect of high-intensity sprint-based exercise remains unknown and was therefore examined in the present study. Following ethical approval and familiarisation, 44 adolescents (12.6 ± 0.6 y) completed an exercise (E) and resting (R) trial in a counter-balanced, randomised crossover design. The exercise trial comprised of 10 × 10 s running sprints, interspersed by 50 s active recovery (walking). A battery of cognitive function tests (Stroop, Digit Symbol Substitution (DSST) and Corsi blocks tests) were completed 30 min pre-exercise, immediately post-exercise and 45 min post-exercise. Data were analysed using mixed effect models with repeated measures. Response times on the simple level of the Stroop test were significantly quicker 45 min following sprint-based exercise (R: 818 ± 33 ms, E: 772 ± 26 ms; p = 0.027) and response times on the complex level of the Stroop test were quicker immediately following the sprint-based exercise (R: 1095 ± 36 ms, E: 1043 ± 37 ms; p = 0.038), while accuracy was maintained. Sprint-based exercise had no immediate or delayed effects on the number of items recalled on the Corsi blocks test (p = 0.289) or substitutions made during the DSST (p = 0.689). The effect of high intensity sprint-based exercise on adolescents' cognitive function was dependant on the component of cognitive function examined. Executive function was enhanced following exercise, demonstrated by improved response times on the Stroop test, whilst visuo-spatial memory and general psycho-motor speed were unaffected. These data support the inclusion of high-intensity sprint-based exercise for adolescents during the school day to enhance cognition.