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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.


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.


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.


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.

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