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Nederveen J.P.,Canadian Center for Activity and Aging | Nederveen J.P.,University of Western Ontario | Keir D.A.,Canadian Center for Activity and Aging | Keir D.A.,University of Western Ontario | And 6 more authors.
Respiratory Physiology and Neurobiology | Year: 2017

We examined the effect of heavy-intensity ‘priming’ exercise on the rate of adjustment of pulmonary O2 uptake (τV˙O2p) initiated from elevated intensities. Fourteen men (separated into two groups: τV˙O2p ≤ 25s [Fast] or τV˙O2p > 25s [Slow]) completed step-transitions from 20 W to 45% lactate threshold (LT; lower-step, LS) and 45% to 90%LT (upper-step, US) performed (i) without; and (ii) with US preceded by heavy-intensity exercise (HUS). Breath-by-breath V˙O2p and near-infrared spectroscopy-derived muscle deoxygenation ([HHb + Mb]) were measured. Compared to LS, τV˙O2p was greater (p < 0.05) in US in both Fast (LS, 19 ± 4s; US, 30 ± 4s) and Slow (LS, 25 ± 5s; US, 40 ± 11s) with τV˙O2p in US being lower (p < 0.05) in Fast. In HUS, τV˙O2p in Slow was reduced (28 ± 8s, p < 0.05) and was not different (p > 0.05) from LS or Fast group US. In Slow, τ[HHb + Mb] increased (p < 0.05) in US relative to HUS; this finding coupled with a reduced τV˙O2p indicates a priming-induced improvement in matching of muscle O2 delivery-to-O2 utilization during transitions from elevated intensities in those with Slow but not Fast V˙O2p kinetics. © 2016 Elsevier B.V.


Murias J.M.,University of Calgary | Edwards J.A.,Canadian Center for Activity and Aging | Edwards J.A.,University of Western Ontario | Paterson D.H.,Canadian Center for Activity and Aging | Paterson D.H.,University of Western Ontario
Scandinavian Journal of Medicine and Science in Sports | Year: 2016

This study examined the time course of short-term training and detraining-induced changes in oxygen uptake (V ˙ O 2) kinetics. Twelve men (24±3 years) were assigned to either a 50% or a 70% of V ˙ O 2 m a x training intensity (n=6 per group). V ˙ O 2 was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration (Δ[HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient V ˙ O 2 and Δ[HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [ H H b ] / V ˙ O 2 ratio was calculated. Similar changes in time constant of V ˙ O 2 (t V ˙ O 2) were observed in both groups. The combined group mean for t V ˙ O 2 decreased ∼14% (32.3 to 27.9s, P<0.05) after one training session with a further ∼11% decrease (27.9 to 24.8s, P<0.05) following two training sessions. The t V ˙ O 2 p remained unchanged throughout the remaining of training and detraining. A significant "overshoot" in the [ H H b ] / V ˙ O 2 ratio was decreased (albeit not significant) after one training session, and abolished (P<0.05) after the second one, with no overshoot observed thereafter. Speeding of V ˙ O 2 kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O2 delivery to O2 utilization is a mechanism proposed to influence this response. © 2016 John Wiley & Sons A/S.


Murias J.M.,Canadian Center for Activity and Aging | Murias J.M.,University of Western Ontario | Spencer M.D.,Canadian Center for Activity and Aging | Spencer M.D.,University of Western Ontario | And 2 more authors.
Exercise and Sport Sciences Reviews | Year: 2014

It has been proposed that the adjustment of oxygen uptake (V̇O 2) during the exercise on-transient is controlled intracellularly in young healthy individuals and that insufficient local O2 delivery plays a rate-limiting role in aging and disease only. This review shows that adequate O2 provision to the active tissues is critical in the dynamic adjustment of oxidative phosphorylation even in young healthy individuals. © 2013 by the American College of Sports Medicine.


Murias J.M.,Canadian Center for Activity and Aging | Murias J.M.,University of Western Ontario | Spencer M.D.,Canadian Center for Activity and Aging | Spencer M.D.,University of Western Ontario | And 6 more authors.
Journal of Applied Physiology | Year: 2011

The relationship between the adjustment of muscle deoxygenation (Δ[HHb]) and phase II V O2p during moderate-intensity exercise was examined before (Mod 1) and after (Mod 2) a bout of heavy-intensity "priming" exercise. Moderate intensity V O2p and Δ [HHb] kinetics were determined in 18 young males (26 ± 3 yr). V O2p was measured breath-by-breath. Changes in Δ [HHb] of the vastus lateralis muscle were measured by near-infrared spectroscopy. V O2p and Δ [HHb] response profiles were fit using a monoexponential model, and scaled to a relative % of the response (0 -100%). The Δ [HHb]/V? O 2 ratio for each individual (reflecting the local matching of O 2 delivery to O 2 utilization) was calculated as the average Δ [HHb]/ V ? O 2 response from 20 s to 120 s during the exercise on-transient. Phase II τV O2p was reduced in Mod 2 compared with Mod 1 (P < 0.05). The effective τ' Δ [HHb] remained the same in Mod 1 and Mod 2 (P > 0.05). During Mod 1, there was an "overshoot" in the Δ [HHb]/V? O 2 ratio (1.08; P > 0.05) that was not present during Mod 2 (1.01; P < 0.05). There was a positive correlation between the reduction in the Δ [HHb]/V? O 2 ratio and the smaller τV O2p from Mod 1 to Mod 2 (r = 0.78; P < 0.05). This study showed that a smaller τV O2p during a moderate bout of exercise subsequent to a heavy-intensity priming exercise was associated with improved microvascular O 2 delivery during the on-transient of exercise, as suggested by a smaller Δ [HHb]/VO 2 ratio. Copyright © 2011 the American Physiological Society.


Petrella R.J.,Canadian Center for Activity and Aging | Cogliano A.,The London Clinic | Decaria J.,Canadian Center for Activity and Aging | Mohamed N.,801 Commissioners Road | Lee R.,University of Waterloo
Sports Medicine, Arthroscopy, Rehabilitation, Therapy and Technology | Year: 2010

Objectives: To determine the efficacy and safety of peri-articular hyaluronic acid injections in chronic lateral epicondylosis (tennis elbow).Design: Prospective randomized clinical trial in primary care sport medicine.Patients: Three hundred and thirty one consecutive competitive racquette sport athletes with chronic (>3 months) lateral epicondylosis were administered 2 injections (first injection at baseline) into the subcutaneous tissue and muscle 1 cm. from the lateral epicondyle toward the primary point of pain using a two-dimensional fanning technique. A second injection was administered 1 week later.Outcomes measures: Assessments were done at baseline, days 7, 14, 30, 90 and 356. Efficacy measures included patient's visual analogue scale (VAS) of pain at rest (0-100 mm) and following assessment of grip strength (0-100 mm). Grip strength was determined using a jamar hydraulic hand dynamometer. Other assessments included patients' global assessment of elbow injury (5 point categorical scale; 1 = no disability, 5 = maximal disability), patients' assessment of normal function/activity (5 point categorical scale), patients/physician satisfaction assessment (10 point categorical scale), time to return to pain-free and disability-free sport and adverse events as per WHO definition. Differences between groups were determined using an intent-to-treat ANOVA.Results: Average age of the study population was 49 years (± 12 years). One hundred and sixty-five patients were randomized to the HA and 166 were randomized to the control groups. The change in VAS pain was -6.7 (± 2.0) for HA vs -1.3 (± 1.5) for control (p < 0.001). The VAS post handgrip was -7.8 (± 1.3) vs +0.3 (± 2.0) (p < 0.001) which corresponded to a significant improvement in grip of 2.6 kg in the HA vs control groups (p < 0.01). Statistically significant improvement in patients' global assessment of elbow injury (p < 0.02), patients' assessment of normal function/activity (p < 0.05) and patients/physician satisfaction assessment (p < 0.05) were also observed favoring the HA group. Time to return to pain-free and disability-free sport was 18 (± 11) days in the HA group but was not achieved in the control group. VAS changes were maintained in the HA group at each followup while those in the control significantly declined from baseline. Assessment of patient and physician satisfaction continued to favor the HA group at subsequent followup.Conclusion: Peri-articular HA treatment for tennis elbow was significantly better than control in improving pain at rest and after maximal grip testing. Further, HA treatment was highly satisfactory by patients and physicians and resulted in better return to pain free sport compred to control. © 2010 Petrella et al; licensee BioMed Central Ltd.


PubMed | University of Calgary and Canadian Center for Activity and Aging
Type: Journal Article | Journal: Scandinavian journal of medicine & science in sports | Year: 2016

This study examined the time course of short-term training and detraining-induced changes in oxygen uptake ( V O 2 ) kinetics. Twelve men (243 years) were assigned to either a 50% or a 70% of V O 2 m a x training intensity (n=6 per group). V O 2 was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration ([HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient V O 2 and [HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [ H H b ] / V O 2 ratio was calculated. Similar changes in time constant of V O 2 ( t V O 2 ) were observed in both groups. The combined group mean for t V O 2 decreased 14% (32.3 to 27.9s, P<0.05) after one training session with a further 11% decrease (27.9 to 24.8s, P<0.05) following two training sessions. The t V O 2 p remained unchanged throughout the remaining of training and detraining. A significant overshoot in the [ H H b ] / V O 2 ratio was decreased (albeit not significant) after one training session, and abolished (P<0.05) after the second one, with no overshoot observed thereafter. Speeding of V O 2 kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O2 delivery to O2 utilization is a mechanism proposed to influence this response.


PubMed | Canadian Center for Activity and Aging
Type: Journal Article | Journal: The Journal of sports medicine and physical fitness | Year: 2015

The aim of this paper was to examine the independent influence of cardiorespiratory fitness and sedentary behavior on chronic disease incidence and body composition in older adults.A sample of 292 community dwelling men and women (mean 69.38.1 years) underwent maximal treadmill testing and completed questionnaires relating to their leisure-time physical activity, sedentary time, and health.The average V O2 of the sample was approximately 21 ml.kg(-1).min(-1) with the average sedentary time being over 3 hours per day. Cardiorespiratory fitness was found to be a stronger predictor of number of chronic conditions and BMI than total physical activity and sedentary. Those with a higher cardiorespiratory fitness had fewer chronic conditions and a lower BMI. No such associations were seen for either total physical activity levels or sedentary time.Cardiorespiratory fitness is a stronger predictor of health among older adults and further highlights the importance of promoting public health guidelines for cardiorespiratory fitness.

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