The effect of high-intensity rowing and combined strength and endurance training on left ventricular systolic function and morphology.

Combined strength and endurance training may result in alterations in left ventricular (LV) systolic function and morphology, however, the acute effect of high-intensity rowing exercise and concurrent training-induced adaptations on LV systolic function are not well known. The purpose of this investigation was to assess LV systolic function before and after a simulated 2000-m rowing race on a Concept II rowing ergometer and evaluate these adaptations following 10 weeks of concurrent strength and endurance training. Furthermore, resting LV morphology was assessed prior to and following the 10-week training program. Ten male subjects underwent two-dimensional echocardiograms at rest, immediately following (95 +/- 27 s), as well as 5 and 45 minutes after, a simulated 2000-m rowing race. These measurements were also made before and after 10 weeks of training. Irrespective of testing time, performance of a 2000-m rowing race resulted in an increase in fractional area change (0.51 +/- 0.06 vs. 0.63 +/- 0.09; p < 0.05) due to an increase in LV contractility. Concurrent strength and endurance training resulted in an increase in the resting LV diastolic cavity area (20.64 +/- 2.59 vs. 22.82 +/- 2.17 cm (2); p < 0.05), end systolic myocardial area (23.27 +/- 4.86 vs. 24.56 +/- 4.00 cm (2); p < 0.05) and LV mass (179.07 +/- 46.91 g vs. 210.46 +/- 51.13 g; p < 0.05). These findings suggest that the acute increase in LV systolic function following a simulated 2000-m rowing race was due to heightened LV contractile reserve. Further, 10 weeks of combined strength and endurance training resulted in an increase in resting LV diastolic cavity size, wall thickness and mass.

The effect of concurrent endurance and strength training on quantitative estimates of subsarcolemmal and intermyofibrillar mitochondria.

We examined the effect of combined strength and endurance training on quantitative estimates of mitochondria in subsarcolemmal and intermyofibrillar regions of muscle fibers. Ten subjects (five males, five females) participated in a 12 week program of combined strength and endurance training. Seven subjects (three males and four females) served as controls. Biopsy samples from the vastus lateralis were obtained before and after training in both groups and also at the mid-point of training in the exercise group. Measurement of succinate dehydrogenase activity throughout muscle fibers, as a quantitative estimate of mitochondrial subpopulations, revealed no differences between exercise and control groups before and after training. Within the exercise group, there was a significant increase in succinate dehydrogenase activity in all regions of muscle fibers from before to after training. There was also a significant increase in succinate dehydrogenase activity in the subsarcolemmal, relative to the intermyofibrillar region from mid-(six weeks) to after-training ( regional distribution x time; p < 0.05). This may have been associated with an oxidative shift in fiber types, as type I fiber percentage was increased in the exercise, compared to the control group (group x time; p < 0.05). We conclude that mitochondrial populations undergo differential changes throughout training. IMF mitochondria increase in a linear manner throughout training, while SS mitochondria undergo a preferential increase late in training. This increase late in training may be related to an increase in proportion of type I fibers.

Effects of creatine monohydrate supplementation during combined strength and high intensity rowing training on performance.

This study investigated the effect of creatine monohydrate (Cr) supplementation on performance and training volume in rowers. Twenty-two rowers trained with continuous and interval rowing and resistance training 4 and 2 days/week, respectively, for 6 weeks. Cr supplementation consisted of a 5-day load (0.3 g/kg(-1) x day(-1)) followed by a 5-week maintenance dose (0.03 g/kg(-1) x day(-1)) while training. Five days of Cr loading did not change body composition, repeated interval rowing performance, 2,000-m rowing times, or strength performance. Five additional weeks of training with a maintenance dose of Cr or placebo significantly improved body composition, VO2max, 2,000-m rowing times, repeated power interval performance, and strength to a similar extent in both groups. Subjects training with Cr did not perform more repetitions per set of strength exercise nor produce or maintain higher power outputs during repeated rowing sessions. Cr supplementation did not increase performance or training volume over a placebo condition in rowers that performed a combined high intensity rowing and strength program.

The effect of strength training on estimates of mitochondrial density and distribution throughout muscle fibres.

The purpose of this study was to investigate the effect of strength training (12 weeks, 3 days/week, four lower-body exercises) of young individuals (mean age 23.6 years) on estimates of mitochondrial distribution throughout muscle fibres. A control group (mean age 21. 7 years) was followed simultaneously. Skeletal muscle biopsy samples were obtained from the vastus lateralis, pre- and post-training. The regional distribution of subsarcolemmal and intermyofibrillar mitochondrial populations was determined using quantitative histochemical staining of succinate dehydrogenase (SDH) in type I and II muscle fibres. Strength training resulted in significant increases of 26% and 28% in the cross-sectional area of type I and II fibres, respectively (P < 0.05). Overall SDH activity decreased by 13% with strength training (P < 0.05). The decrease in SDH activity with strength training between fibre types and between subsarcolemmal and intermyofibrillar regions of muscle fibres was not different. Fibre area and SDH activity was unchanged in the control group. We conclude that the muscle hypertrophy associated with strength training results in reduced density of regionally distributed mitochondria, as indicated by the reduction in the activity of SDH.

Exercise after acute hyperbaric oxygenation: is there an ergogenic effect?

The purpose of this study was to determine the effects of a 1-h exposure to 2.0 atm abs (202.6 kPa) and 100% oxygen on subsequent maximal O2 consumption (VO2max), ventilation threshold (VT), lactate threshold (LT), and muscle oxygenation (%Mox) during incremental exercise to maximum on a cycle ergometer. Two baseline exercise tests (T1 and T2) were performed on separate occasions without prior exposure to hyperbaric oxygen (HBO2) and a third test (T3-HBO2) was performed after (22.5 +/- 5.6 min) HBO2 Near infared spectroscopy was used to monitor oxygenation of the left vastus lateralis muscle during T2 and T3-HBO2. No significant differences were observed between VO2max VT, or LT among any of the exercise tests. There was no significant difference in %Mox between T2 and T3-HBO2 except at 235 W where there was a significant elevation in %Mox during T3-HBO2 relative to T2. These results suggest that prior exposure to HBO2 (100% O2 at 2 atm abs for 1 h) has no ergogenic effect on subsequent incremental exercise performance.

Position of the cervical vertebrae during helmet removal and cervical collar application in football and hockey.

There is lack of consensus among prehospital personnel (athletic therapists, paramedics, sport physiotherapists) concerning specific aspects of initial care and assessment of injured athletes presenting signs and symptoms of a cervical spine injury (CSI). In instances of serious injury involving the head and/or spine, complicated by altered levels of consciousness, protective equipment such as helmets and shoulder pads may provide a hinderance to prompt, safe and efficient management. Specifically, there is disagreement concerning the need or advisability of removing protective head gear, as in the case of football and hockey athletes. Using the technique of fluoroscopy, the cervical spine displacement of 21 male football and hockey athletes was determined while wearing protective shoulder pads and protective head equipment at the following times (a) during helmet removal, (b) during cervical collar application, and (c) as the helmetless head was allowed to rest. Subsequent frame-by-frame video arthokinematic analysis, using computer-assisted digitization, showed significant alterations in the position of adjacent cervical vertebrae during helmet removal, cervical collar application, and head rest. Results suggest that stabilization and transportation of football and hockey athletes with suspected CSI in their respective protective equipment is recommended in order to reduce the risk of further trauma by unnecessary cervical spine motion.

Maintenance of strength gains while performing endurance training in oarswomen.

This study investigated the retention of strength gained after resistance training, while performing aerobic endurance training. Following a 10-week resistance training program (three times a week) that included maintenance aerobic endurance training (twice a week), 18 varsity oarswomen were matched on strength and randomly assigned to two groups: Group 1 performed maintenance resistance training once a week and Group 2 performed resistance training twice a week. Both groups performed endurance training four times a week during the 6-week maintenance resistance training program. There was a significant increase in strength (multiple-RM test) for three upper and three lower body exercises after the initial 10-week resistance training program. A further significant increase in two exercises (inclined leg press and knee flexion) were observed after 6 weeks of maintenance resistance training and endurance training in both groups. No further significant increases were observed in the four other exercises during maintenance strength training. These latter findings occurred at the same time that VO2max and ventilation threshold increased. These results suggest that strength gains can be maintained with resistance training once or twice a week while focusing on improving aerobic endurance performance without compromising the latter.