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PhD in Sport and Exercise Science
Faculty of Health and Life Sciences
01865 48 3610
Helena kennedy, room F106
I teach on several module at undergraduate level, including anatomy, biomechanics and sport training principles. I also teach on postgraduate modules for the MSc in Sport and Exercise Nutrition and Applied Human Nutrition, including research methods and laboratory techniques for sport and exercise nutrition.
Iam also the department chair for the research ethics committee
I teach on several modules at undergraduate and postgraduate level.
I also supervise undergraduate and postgraduate students for their dissertations
U76201 Anatomy for Sport and exercise
P16504 Research methods
P16510 Laboratory Techniques for Sport and Exercise Nutrition
Iam supervising several MSc students every year on projects linked to the benefits of sports supplements on physical performance.
iam also currently supervising two PhD students:
Erin Hannink "exploration of sagittal plane deformity"
Daniel Newcombe "The Environment Design Framework – Bridging the gap between the theoretical understanding and the practical application of a constraints-led approach"
My current research projects are:
Brain plasticity and motor skill competence development in young people with Development Coordination Disorder (Movement science group)
Strengthening strategies to reduce the risk oh hamstrings injuries in feamle football players
This study sought to select the most relevant test items from the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOTMP-2) and from a selection of health-related fitness tests for identifying school teenagers with poor motor coordination. The 241 participants in this study (144 boys, 97 girls aged 13–14 years old) were tested on the short form of the BOTMP-2 and on the following additional fitness tests: (a) seated medicine ball test, (b) broad jump, (c) handgrip strength, (d) alternate hand ball wall toss, (e) 10 × 5-meter agility shuttle run, and (f) Chester step test. We performed a factor analysis of participant scores on these various tasks and BOTMP-2 test items to reduce them to the least number of meaningful and useful items. Four factors explained 45% of the data variance: gross motor skills and power (including broad jump, hand ball toss, shuttle run, and sit-ups tests); fine motor skills (including copying star, following the maze and paper folding); core strength and balance (including push-ups, hopping, and balance beam); and general body strength (including medicine ball throw and handgrip). We conclude that an efficient school-based battery of test items to screen 13-14 year old adolescents for fitness and coordination should assess these four factors and might especially rely upon the broad jump, copying a star shape, hopping handgrip strength, aerobic fitness, and wall ball toss.
Purpose: The aim was to identify benefits of compression garments used for recovery of exercised-induced muscle damage. Methods: Computer-based literature research was performed in September 2015 using four online databases: Medline (PubMed), Cochrane, WOS (Web Of Science) and Scopus. The analysis of risk of bias was completed in accordance with the Cochrane Collaboration Guidelines. Mean differences and 95% confidence intervals were calculated with Hedges' g for continuous outcomes. A random effect meta-analysis model was used. Systematic differences (heterogeneity) were assessed with I statistic. Results: Most results obtained had high heterogeneity, thus their interpretation should be careful. Our findings showed that creatine kinase (standard mean difference = - 0.02, 9 studies) was unaffected when using compression garments for recovery purposes. In contrast, blood lactate concentration was increased (standard mean difference = 0.98, 5 studies). Applying compression reduced lactate dehydrogenase (standard mean difference = - 0.52, 2 studies), muscle swelling (standard mean difference = - 0.73, 5 studies) and perceptual measurements (standard mean difference = - 0.43, 15 studies). Analyses of power (standard mean difference = 1.63, 5 studies) and strength (standard mean difference = 1.18, 8 studies) indicate faster recovery of muscle function after exercise. Conclusions: These results suggest that the application of compression clothing may aid in the recovery of exercise induced muscle damage, although the findings need corroboration.
The objectives were to compare the metabolic load elicited by Zumba classes and DVD workouts and link the physiological responses to participants’ psychological characteristics. Fifteen women (25.4 ± 4.3 years old; 164.9 ± 5.1 cm; 56.9 ± 5.8 kg; 23.9 ± 4.9% body fat) performed three Zumba classes and three Zumba DVD workouts using a repeated measure design. Energy expenditure was assessed by extrapolating oxygen cost from heart rate (HR) using regressions from a preliminary incremental running test. Differences between Zumba classes and Zumba DVD workouts were assessed by Student’s T tests and repeated measures analysis of variance and correlations between physiological and psychological variables by the Pearson’s coefficient. Results showed that Zumba classes allowed greater energy expenditure compared to Zumba DVD workouts (6.8 ± 0.9 vs 5.6 ± 0.9 kcal · min, 95% confidence interval (CI) limits: 0.3–2.1, P = 0.016), with significant differences in the time spent with a HR above 85% of HR reserve (14.7 vs 1.7%, 95% CI: 5.6–20.4, P = 0.021). Furthermore, women with a greater autonomy score showed a smaller difference between DVD and class (r = 0.511, P = 0.048), while greater differences were shown in women with greater interpersonal skills (r = −0.563, P = 0.028). The results suggest that while both types of workouts are suitable to maintain fitness Zumba classes allow greater energy expenditure.
There is no current study that examined sport-specific tests of reactive-agility and change-of-direction-speed (CODS) to repli-cate real-sport environment in handball (team-handball). This investigation evaluated the reliability and validity of two novel tests designed to assess reactive-agility and CODS of handball players. Participants were female (25.14 ± 3.71 years of age; 1.77 ± 0.09 m and 74.1 ± 6.1 kg) and male handball players (26.9 ± 4.1 years of age; 1.90 ± 0.09 m and 93.90±4.6 kg). Variables included body height, body mass, body mass index, broad jump, 5-m sprint, CODS and reactive-agility tests. Results showed satisfactory reliability for reactive-agility-test and CODS-test (ICC of 0.85-0.93, and CV of 2.4-4.8%). The reac-tive-agility and CODS shared less than 20% of the common variance. The calculated index of perceptual and reactive capaci-ty (P&RC; ratio between reactive-agility- and CODS-performance) is found to be valid measure in defining true-game reactive-agility performance in handball in both genders. There-fore, the handball athletes’ P&RC should be used in the evalua-tion of real-game reactive-agility performance. Future studies should explore other sport-specific reactive-agility tests and factors associated to such performance in sports involving agile maneuvers.
Purpose: To evaluate the effect of simulated soccer on the hamstrings eccentric torque-angle profile and angle of peak torque (APTeccH), and on the hamstrings:quadriceps torque ratio at specific joint angles (ASHecc:Qcon). Methods: The authors assessed dominant-limb isokinetic concentric and eccentric knee flexion and concentric knee extension at 120°/s in 9 semiprofessional male soccer players immediately before and after they completed the Loughborough Intermittent Shuttle Test (LIST). Results: The LIST resulted in significant decreases in eccentric hamstrings torque at 60°, 50°, and 10° and a significant (21.8%) decrease in ASHecc:Qcon at 10° (P < .05). APTeccH increased from 7.1° ± 1.0° to 18.8° ± 4.2° (P < .05). Eccentric hamstrings peak torque significantly declined from 185.1 ± 70.4 N·m pre-LIST to 150.9 ± 58.5 N·m post-LIST (P = .002), but there were no significant changes in hamstrings or quadriceps concentric peak torque (P = .312, .169, respectively). Conclusions: Simulated soccer results in a selective loss of eccentric hamstrings torque and hamstrings-to-quadriceps muscle balance at an extended joint position and a shift in the eccentric hamstrings APT to a shorter length, changes that could increase vulnerability to hamstrings injury. These findings suggest that injury-risk screening could be improved by evaluating the eccentric hamstrings torque-angle profile and hamstrings strength-endurance and that the development of hamstrings fatigue resistance and long-length eccentric strength may reduce injury incidence.
The aim of this study was to investigate the effects of a weight loss intervention based on physical exercise on the relationship between energy cost and stride frequency during walking in obese teenagers. Participants aged 13–16 years old were assigned to a training (n = 14) and control (n = 10) groups. During eight weeks, the training group performed three 60-min weekly sessions of high-intensity intermittent activities coupled with aerobic training. Body composition, gait parameters and energy cost during 4-min walking bouts at participants’ most comfortable speed and preferred stride frequency (PSF), PSF-10%, PSF + 10%, PSF-20% and PSF + 20% were measured before and after intervention. The effects of training and stride frequencies on the energy cost of walking were analysed by an ANOVA with repeated measures. The main results showed that the exercise intervention induced a significant increase in walking speed (+23.2%), and significant decreases in body mass (−1.4%), body fat percentage (−2.1%) and energy cost of walking at various frequencies (decreases ranging from −10.5% to −20.4%, p < .05). In addition, significantly greater decreases were shown at high frequencies (p < .05). No significant differences were shown in the control group (p > .05). These results suggest that this type of training is beneficial to reduce walking energy cost of obese teenagers, in particular at high frequencies. This should improve their well-being during daily activities.
The purpose of this study was to determine the substrate oxidation rate and the exercise intensity at which maximal lipid oxidation and ventilatory threshold (VT) occur in obese (BMI: 36.6 ± 6.3 kg · m−2) and normal-weight adolescent girls (BMI: 18.7 ± 1.6 kg · m−2) aged 14–18 years. Substrate oxidation rate was determined by gas exchange using an incremental field test involving walking. Body composition was assessed by bioelectrical impedance. Carbohydrate oxidation rates were significantly higher in obese than in normal-weight girls at speeds ranging from 4 to 6 km · h−1 (P < 0.05), whereas no significant differences were observed between groups regarding lipid oxidation rates. The crossover point of substrate utilisation and the VT were significantly lower in obese than in normal-weight adolescents (P < 0.05). Maximal lipid oxidation rate was observed at 46 ± 15 and 53 ± 15 %E (Formula presented.) O2max in obese and normal-weight adolescents, respectively. At these intensities, the Lipoxmax was significantly lower in obese than in normal-weight girls (6.7 ± 2.3 versus 8.9 ± 3.5 mg · min−1 · kg−1 FFM, P < 0.05, 95% CI: −3.7 to −0.7, d = −0.74). The present results have implications in designing interventions to promote lipid oxidation and energy expenditure during walking in severely obese adolescent girls.
Purpose: To investigate the reliability and determinants of performance in a new test of planned agility in elite junior basketball players. Methods: Seventeen female (15.1 ± 0.4 y, 176.9 ± 11.2 cm, 65.7 ± 10.9 kg) and 42 male (14.9 ± 0.4 y, 193.7 ± 8.1 cm, 79.0 ± 12.0 kg) elite junior basketball players performed 5 fitness tests presented in a random order, including a 20-m sprint, a planned-agility test, a triple bilateral horizontal countermovement jump, and 2 triple unilateral horizontal countermovement jumps (with each leg separately). The novelty of the planned-agility test is that it included both offensive and defensive movements. The determinants of planned agility were assessed by a stepwise-regression analysis, and the reliability of the new test was evaluated by the intraclass correlation coefficient and the typical error of measurement. Results: The main results show good reliability of the new test of planned agility. In addition, the determinants of planned-agility performance were different between genders, with sprint performance explaining 74.8% of the variance for girls, while unilateral jump performance and body mass were the most important for boys, accounting for 24.0% and 8.9% of the variance, respectively, in planned agility. Conclusions: These results highlight a gender effect on the determinants of planned-agility performance in young elite basketball players and suggest that straight-line sprint and unilateral horizontal tests must be implemented to test elite junior players.
The aim of the study was to investigate the effects of playing an official national-level basketball match on repeated sprint ability (RSA) and stride kinematics.
Nine male starting basketball players (22.8±2.2 years old, 191.3±5.8 cm, 88±10.3 kg, 12.3±4.6% body fat) volunteered to take part. Six repetitions of maximal 4-s sprints were performed on a non-motorised treadmill, separated by 21-s of passive recovery, before and immediately after playing an official match. Fluid loss, playing time, and the frequencies of the main match activities were recorded. The peak, mean, and performance decrement for average and maximal speed, acceleration, power, vertical and horizontal forces, and stride parameters were calculated over the six sprints. Differences between pre- and post-match were assessed by student t-tests.
Significant differences between pre- and post-tests were observed in mean speed (-3.3%), peak and mean horizontal forces (-4.3% and -17.4%), peak and mean vertical forces (-3.4% and -3.7%), contact time (+7.3%), stride duration (+4.6%) and stride frequency (-4.0%), (P<0.05). In addition, the variation in several RSA parameters, such as peak and mean speed, peak and mean acceleration, mean power, and peak and mean vertical force were significantly correlated to fluid loss and sprint, jump and shuffle frequencies (P<0.05).
These results highlight that the impairment in repeated sprint ability depends on the specific activities performed, and that replacing fluid loss through sweating during a match is crucial.
Exercise physiology and biomechanics
Propuesta de small-sided games para deportes indoor: Baloncesto. III Jornadas deActualización en Rendimiento Deportivo,Vitoria, 23rd of September 2016.
Avaliações Físicas no Basquetebol: considerações sobre as posições no jogo. UniversidadeCatólica de Brasília (UCB), Brasil, 25 de Agosto 2015.
Análisis científico de la evolución del juego. V Jornadas de actualización en las áreas demedicina, preparación física y deporte, San Sebastian, Spain, 21-23 June 2012.
Carga externa en baloncesto: Su análisis e interpretatión. V Jornadas de actualización en lasáreas de medicina, preparación física y deporte,” San Sebastian, Spain, 25 June 2011.
Coordination and skill acquisition in team sports: applications to coaching. 11. MeƋunarodnakonferencija “Kondicijska Priprema Sportaša”. Zagreb, 19th of February 2010.
Effects of previous swimming exercise on cycling energy cost in high-level triathletes.Applied Sports Science International Symposium, Anglia Ruskin university, Cambridge, UK,20th of June 2006.
Recent oral communications:
Delextrat A., Bateman, J., Esser, P., Targen, N., and Dawes, H. The potential benefits of Zumba Gold in people with Parkinson’s: a feasibility study. Winter Congress of the Society for Research in Rehabilitation, 2nd of February 2016, London, UK.
Delextrat, A. and Cohen, D.D. Strength-endurance training reduces hamstrings peak torque drop in simulated football. International Conference of Sport Rehabilitation and Traumatology, Football Medicine Strategies for Player Care, London, 11th – 12th April 2015.
Delextrat, A., Baliqi, F., Clarke, N.D. Repeated Sprint Ability And Stride Kinematics Are Altered Following An Official Match In National-level Basketball Players.18th annual congress of the European College of Sport Science – ECSS, Barcelona 2013.
2004- 2012 Senior Lecturer in Sports Science, London Metropolitan University, UK. Exercise physiologist at the Fitness Assessment Centre, London Metropolitan University, UK.
2003-2004 Post-doctoral position, Greenwich University, UK: “Biomechanical analysis of the shooting action in netball”
2000-2003 Part-time lecturer in Sports Science, University of the South, Toulon-Var, France.