Nicolas H. Hart

Effect of strength on plant foot kinetics and kinematics during a change of direction task

Abstract Understanding the magnitude of forces and lower body kinematics that occur during a change of direction (COD) task can provide information about the biomechanical demands required to improve performance. To compare the magnitude of force, impulse, lower body kinematics and post-COD stride velocity produced between athletes of different strength levels during a COD task, 12 stronger (8 males, 4 females) and 12 weaker (4 males, 8 females) recreational team sport athletes were recruited. Strength levels were determined by relative peak isometric force of the dominant and non-dominant leg. All athletes performed 10 pre-planned 45° changes of direction (5 left, 5 right) while three-dimensional motion and ground reaction force (GRF) data were collected. Differences in all variables for the dominant leg were examined using a one-way analysis of variance (ANOVA) with a level of significance set at p ≤0.05. The stronger group displayed significantly faster post-COD stride velocity and greater vertical and horizontal braking forces, vertical propulsive force, vertical braking impulse, horizontal propulsive impulse, angle of peak braking force application, hip abduction and knee flexion angle compared to the weaker group. The results suggest that individuals with greater relative lower body strength produced higher magnitude plant foot kinetics and modified lower body positioning while producing faster COD performances. Future investigations should determine if strength training to enable athletes to increase plant foot kinetics while maintaining or adopting a lower body position results in a concomitant increases in post-COD stride velocity.

Contribution of strength characteristics to change of direction and agility performance in female basketball athletes.

Abstract Spiteri, T, Nimphius, S, Hart, NH, Specos, C, Sheppard, JM, and Newton, RU. Contribution of strength characteristics to change of direction and agility performance in female basketball athletes. J Strength Cond Res 28(9): 2415–2423, 2014—Research has often examined the relationship between 1 or 2 measures of strength and change of direction (COD) ability reporting inconsistent relationships to performance. These inconsistencies may be the result of the strength assessment used and the assumption that 1 measure of strength can represent all “types” of strength required during a COD task. Therefore the purpose of this study was to determine the relationship between several lower-body strength and power measures, COD, and agility performance. Twelve (n = 12) elite female basketball athletes completed a maximal dynamic back squat, isometric midthigh pull, eccentric and concentric only back squat, and a countermovement jump, followed by 2 COD tests (505 and T-test) and a reactive agility test. Pearson product-moment correlation and stepwise regression analysis were performed on all variables. The percentage contribution of each strength measure to an athletes total strength score was also determined. Our results demonstrated that both COD tests were significantly correlated to maximal dynamic, isometric, concentric, and eccentric strength (r = −0.79 to −0.89), with eccentric strength identified as the sole predictor of COD performance. Agility performance did not correlate with any measure of strength (r = −0.08 to −0.36), whereas lower-body power demonstrated no correlation to either agility or COD performance (r = −0.19 to −0.46). These findings demonstrate the importance of multiple strength components for COD ability, highlighting eccentric strength as a deterministic factor of COD performance. Coaches should aim to develop a well-rounded strength base in athletes; ensuring eccentric strength is developed as effectively as the often-emphasized concentric or overall dynamic strength capacity.

Mechanical Determinants of Faster Change of Direction and Agility Performance in Female Basketball Athletes.

Abstract Spiteri, T, Newton, RU, Binetti, M, Hart, NH, Sheppard, JM, and Nimphius, S. Mechanical determinants of faster change of direction and agility performance in female basketball athletes. J Strength Cond Res 29(8): 2205–2214, 2015—Change of direction (COD) and agility require the integration of multiple components to produce a faster performance. However, the mechanisms contributing to a faster performance without the confounding factor of athlete expertise or gender is currently unknown. Therefore, the purpose of this study was to assess body composition, strength, and kinetic profile required for a faster COD and agility performance across multiple directional changes. Six faster and 6 slower (n = 12) elite female basketball athletes completed a maximal dynamic back squat; eccentric and concentric only back squat; isometric midthigh pull; whole-body scan to determine lean, fat, and total mass; 505 COD test; T-test; and a multidirectional agility test over in-ground force plates to obtain relevant kinetic measures. Group (faster and slower) by test (2 × 3) multivariate analyses of variance with follow-up analyses of variance were conducted to examine differences between faster and slower groups and each COD and agility test (p ⩽ 0.05). Faster athletes during the 505 COD test produced significantly greater vertical force (p = 0.002) and eccentric and isometric strength capacity (p = 0.001). Faster agility and T-test athletes demonstrated significantly shorter contact times (p = 0.001), greater propulsive impulse (p = 0.02), isometric strength, and relative lean mass compared with slower athletes. Differences between faster athletes across each test seem to be attributed to the mechanical demands of the directional change, increasing force and impulse application as the degree of directional change increased. These findings indicate that different mechanical properties are required to produce a faster COD and agility performances, and the importance of a greater strength capacity to enable greater mechanical adjustment through force production and body control, during different directional changes.

Leg mass characteristics of accurate and inaccurate kickers - an Australian football perspective

Abstract Athletic profiling provides valuable information to sport scientists, assisting in the optimal design of strength and conditioning programmes. Understanding the influence these physical characteristics may have on the generation of kicking accuracy is advantageous. The aim of this study was to profile and compare the lower limb mass characteristics of accurate and inaccurate Australian footballers. Thirty-one players were recruited from the Western Australian Football League to perform ten drop punt kicks over 20 metres to a player target. Players were separated into accurate (n = 15) and inaccurate (n = 16) groups, with leg mass characteristics assessed using whole body dual energy x-ray absorptiometry (DXA) scans. Accurate kickers demonstrated significantly greater relative lean mass (P ≤ 0.004) and significantly lower relative fat mass (P ≤ 0.024) across all segments of the kicking and support limbs, while also exhibiting significantly higher intra-limb lean-to-fat mass ratios for all segments across both limbs (P ≤ 0.009). Inaccurate kickers also produced significantly larger asymmetries between limbs than accurate kickers (P ≤ 0.028), showing considerably lower lean mass in their support leg. These results illustrate a difference in leg mass characteristics between accurate and inaccurate kickers, highlighting the potential influence these may have on technical proficiency of the drop punt.

Offensive and Defensive Agility: A Sex Comparison of Lower Body Kinematics and Ground Reaction Forces

The aim of this study was to compare biomechanical and perceptual-cognitive variables between sexes during an offensive and defensive agility protocol. Twelve male and female (n = 24) recreational team sport athletes participated in this study, each performing 12 offensive and defensive agility trials (6 left, 6 right) changing direction in response to movements of a human stimulus. Three-dimensional motion, ground reaction force (GRF), and impulse data were recorded across plant phase for dominant leg change of direction (COD) movements, while timing gates and high-speed video captured decision time, total running time, and post COD stride velocity. Subjects also performed a unilateral isometric squat to determine lower body strength and limb dominance. Group (sex) by condition (2 × 2) MANOVAs with follow-up ANOVAs were conducted to examine differences between groups (P ≤ .05). Male athletes demonstrated significantly greater lower body strength, vertical braking force and impulse application, knee and spine flexion, and hip abduction, as well as faster decision time and post COD stride velocity during both agility conditions compared with females. Differences between offensive and defensive movements appear to be attributed to differences in decision time between sexes. This study demonstrates that biomechanical and perceptual-cognitive differences exist between sexes and within offensive and defensive agility movements.

Musculoskeletal asymmetry in football athletes: a product of limb function over time

PURPOSE Asymmetrical loading patterns are commonplace in football sports. Our aim was to examine the influence of training age and limb function on lower-body musculoskeletal morphology. METHODS Fifty-five elite football athletes were stratified into less experienced (≤3 yr; n = 27) and more experienced (>3 yr; n = 28) groups by training age. All athletes underwent whole-body dual-energy x-ray absorptiometry scans and lower-body peripheral quantitative computed tomography tibial scans on the kicking and support limbs. RESULTS Significant interactions between training age and limb function were evident across all skeletal parameters (F16, 91 = 0.182, P = 0.031, Wilks Λ = 0.969). Asymmetries between limbs were significantly larger in the more experienced players than the less experienced players for tibial mass (P ≤ 0.044, d ≥ 0.50), total cross-sectional area (P ≤ 0.039, d ≥ 0.53), and stress-strain indices (P ≤ 0.050, d ≥ 0.42). No significant asymmetry was evident for total volumetric density. More experienced players also exhibited greater lower-body tibial mass (P ≤ 0.001, d ≥ 1.22), volumetric density (P ≤ 0.009, d ≥ 0.79), cross-sectional area (P ≤ 0.387, d ≥ 0.21), stress-strain indices (P ≤ 0.012, d ≥ 0.69), fracture loads (P ≤ 0.018, d ≥ 0.57), and muscle mass and cross-sectional area (P ≤ 0.016, d ≥ 0.68) than less experienced players. CONCLUSIONS Asymmetries were evident in athletes as a product of limb function over time. Chronic exposure to routine high-impact gravitational loads afforded to the support limb preferentially improved bone mass and structure (cross-sectional area and cortex thickness) as potent contributors to bone strength relative to the high-magnitude muscular loads predominantly afforded to the kicking limb.

Exercise Preserves Physical Function in Prostate Cancer Patients with Bone Metastases

PurposeThe presence of bone metastases has excluded participation of cancer patients in exercise interventions and is a relative contraindication to supervised exercise in the community setting because of concerns of fragility fracture. We examined the efficacy and safety of a modular multimodal exercise program in prostate cancer patients with bone metastases. MethodsBetween 2012 and 2015, 57 prostate cancer patients (70.0 ± 8.4 yr; body mass index, 28.7 ± 4.0 kg·m−2) with bone metastases (pelvis, 75.4%; femur, 40.4%; rib/thoracic spine, 66.7%; lumbar spine, 43.9%; humerus, 24.6%; other sites, 70.2%) were randomized to multimodal supervised aerobic, resistance, and flexibility exercises undertaken thrice weekly (EX; n = 28) or usual care (CON; n = 29) for 3 months. Physical function subscale of the Medical Outcomes Study Short-Form 36 was the primary end point as an indicator of patient-rated physical functioning. Secondary end points included objective measures of physical function, lower body muscle strength, body composition, and fatigue. Safety was assessed by recording the incidence and severity of any adverse events, skeletal complications, and bone pain throughout the intervention. ResultsThere was a significant difference between groups for self-reported physical functioning (3.2 points; 95% confidence interval, 0.4–6.0 points; P = 0.028) and lower body muscle strength (6.6 kg; 95% confidence interval, 0.6–12.7; P = 0.033) at 3 months favoring EX. However, there was no difference between groups for lean mass (P = 0.584), fat mass (P = 0.598), or fatigue (P = 0.964). There were no exercise-related adverse events or skeletal fractures and no differences in bone pain between EX and CON (P = 0.507). ConclusionsMultimodal modular exercise in prostate cancer patients with bone metastases led to self-reported improvements in physical function and objectively measured lower body muscle strength with no skeletal complications or increased bone pain.Trial Registration: ACTRN12611001158954.

Exercise medicine for advanced prostate cancer

Purpose of review Exercise is a provocative medicine, known for its preventive, complimentary and rehabilitative role in the management of cancer. Impressively, exercise is also emerging as a synergistic and targeted medicine to enhance symptom control, modulate tumour biology and delay disease progression, with the potential to increase overall survival. Given the complex clinical presentation of advanced prostate cancer patients and their omnipresent comorbidities, this review describes the current and potential role of exercise medicine in advanced prostate cancer. Recent findings Exercise has been shown to be safe, feasible and effective for advanced prostate cancer patients, inclusive of patients with bone metastases; a previously excluded population due to patient and clinician fear of adverse events. Preclinical data provide insight into the ability of exercise to modulate cancer-specific outcomes, may synergistically increase the potency of chemotherapy and radiotherapy and may endogenously and/or mechanically suppress tumour formation, growth and invasion in visceral and skeletal tissue. Epidemiological studies have also shown an association between physical activity and increased survival. Summary Exercise oncology is rapidly evolving, with impressive possibilities that may directly improve patient outcomes in advanced prostate cancer. Research must focus on translating preclinical trials into human clinical trials and investigate the direct effect of exercise on overall survival.

Can exercise suppress tumour growth in advanced prostate cancer patients with sclerotic bone metastases? A randomised, controlled study protocol examining feasibility, safety and efficacy

Introduction Exercise may positively alter tumour biology through numerous modulatory and regulatory mechanisms in response to a variety of modes and dosages, evidenced in preclinical models to date. Specifically, localised and systemic biochemical alterations produced during and following exercise may suppress tumour formation, growth and distribution by virtue of altered epigenetics and endocrine–paracrine activity. Given the impressive ability of targeted mechanical loading to interfere with metastasis-driven tumour formation in human osteolytic tumour cells, it is of equal interest to determine whether a similar effect is observed in sclerotic tumour cells. The study aims to (1) establish the feasibility and safety of a combined modular multimodal exercise programme with spinal isometric training in advanced prostate cancer patients with sclerotic bone metastases and (2) examine whether targeted and supervised exercise can suppress sclerotic tumour growth and activity in spinal metastases in humans. Methods and analysis A single-blinded, two-armed, randomised, controlled and explorative phase I clinical trial combining spinal isometric training with a modular multimodal exercise programme in 40 men with advanced prostate cancer and stable sclerotic spinal metastases. Participants will be randomly assigned to (1) the exercise intervention or (2) usual medical care. The intervention arm will receive a 3-month, supervised and individually tailored modular multimodal exercise programme with spinal isometric training. Primary endpoints (feasibility and safety) and secondary endpoints (tumour morphology; biomarker activity; anthropometry; musculoskeletal health; adiposity; physical function; quality of life; anxiety; distress; fatigue; insomnia; physical activity levels) will be measured at baseline and following the intervention. Statistical analyses will include descriptive characteristics, t-tests, effect sizes and two-way (group × time) repeated-measures analysis of variance (or analysis of covariance) to examine differences between groups over time. The data-set will be primarily examined using an intention-to-treat approach with multiple imputations, followed by a secondary sensitivity analysis to ensure data robustness using a complete cases approach. Ethics and dissemination Ethics approval was obtained from the Human Research Ethics Committee (HREC) of Edith Cowan University and the Sir Charles Gairdner and Osborne Park Health Care Group. If proven to be feasible and safe, this study will form the basis of future phase II and III trials in human patients with advanced cancer. To reach a maximum number of clinicians, practitioners, patients and scientists, outcomes will be disseminated through national and international clinical, conference and patient presentations, as well as publication in high-impact, peer-reviewed academic journals. Trial registration number ACTRN 12616000179437.

Activity behaviors and physiological characteristics of women with advanced-stage ovarian cancer: A preliminary cross-sectional investigation

Objectives Ovarian cancer (OC) survivors experience many disease and treatment adverse effects. However, the impact of OC and its treatment on objective activity behaviors and physiological status have not been examined. The purpose of this study was to compare objectively measured activity behaviors and physiological characteristics of advanced-stage OC survivors to age-matched controls. Methods Twenty stage III–IV OC survivors and 20 controls completed assessments of activity behaviors (7-day accelerometry), physical function (400-meter walk as indicator of cardiorespiratory fitness, repeated chair rise, 6-meter walking tests), muscle strength (1-repetition maximum and handgrip), body composition (dual-energy x-ray absorptiometry), and musculoskeletal morphology (peripheral quantitative computed tomography). Results Compared with controls, OC survivors spent more time/day in prolonged sedentary bouts (P = 0.039, r = 0.32), had lower cardiorespiratory fitness (P = 0.041, r = 0.33) and upper body strength (P = 0.023, r = 0.37), had higher areal bone mineral content (P = 0.047, r = 0.33) and volumetric trabecular density (P = 0.048, r = 0.31), but were not different in other measures of body composition nor in muscle morphology (P > 0.050). Only 20% (n = 4) of OC survivors accrued 150 minutes/week or greater moderate and vigorous physical activity (MVPA) time in 10-minute bouts or greater. Moderate and vigorous physical activity time/day in 10-minute bouts or greater was strongly associated with cardiorespiratory fitness (P = 0.001, ρ = −0.702) and lower extremity function (P = 0.019, ρ = −0.519) and moderately associated with muscle cross-sectional area (P = 0.035, ρ = 0.473). Conclusions Posttreatment OC survivors spent more time in prolonged sedentary bouts and had lower cardiorespiratory fitness and upper body strength compared with controls. Moderate and vigorous physical activity was associated with physical function and muscle cross-sectional area. Future studies should test the efficacy of exercise interventions to increase MVPA, reduce sedentary behavior, and increase cardiorespiratory fitness and muscle strength in OC survivors.