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Louisa Beale, Neil S Maxwell, Oliver R Gibson, Rosemary Twomey, Becky Taylor and Andrew Church

Background:

The purpose of this study was to characterize the physiological demands of a riding session comprising different types of recreational horse riding in females.

Methods:

Sixteen female recreational riders (aged 17 to 54 years) completed an incremental cycle ergometer exercise test to determine peak oxygen consumption (VO2peak) and a 45-minute riding session based upon a British Horse Society Stage 2 riding lesson (including walking, trotting, cantering and work without stirrups). Oxygen consumption (VO2), from which metabolic equivalent (MET) and energy expenditure values were derived, was measured throughout.

Results:

The mean VO2 requirement for trotting/cantering (18.4 ± 5.1 ml·kg-1·min-1; 52 ± 12% VO2peak; 5.3 ± 1.1 METs) was similar to walking/trotting (17.4 ± 5.1 ml·kg-1·min-1; 48 ± 13% VO2peak; 5.0 ± 1.5 METs) and significantly higher than for work without stirrups (14.2 ± 2.9 ml·kg-1·min-1; 41 ± 12% VO2peak; 4.2 ± 0.8 METs) (P = .001).

Conclusion:

The oxygen cost of different activities typically performed in a recreational horse riding session meets the criteria for moderate intensity exercise (3-6 METs) in females, and trotting combined with cantering imposes the highest metabolic demand. Regular riding could contribute to the achievement of the public health recommendations for physical activity in this population.

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Viswanath B. Unnithan, Ellinor M. Kenne, Lynne Logan, Scott Collier and Margaret Turk

The aim of this study was to assess the effect of partial body weight support on the oxygen cost of treadmill walking in children and adolescents with spastic cerebral palsy (CP). Five children and adolescents (2 girls and 3 boys) with spastic CP (12.4 ± 3.6 years) volunteered for the study. Participants performed three 4-min tread mill walks on three separate days at their comfortable treadmill walking speeds. At each visit a different partial body weight harness setting was used. Significant (p < .05) differences in oxygen cost were found when the harness was worn but not connected to the support frame. Partial body weight support reduces the oxygen cost of walking in children and adolescents with spastic CP.

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John L. Walker, Tinker D. Murray, Charles M. Johnson, Don L. Rainey and William G. Squires Jr.

This study evaluated the aerobic demands of the 20-minute steady-state jogging speeds for 15 high school students. All subjects performed a discontinuous treadmill test that included submaximal speeds, the Fit Youth Today criterion referenced speeds, and finally a run to voluntary fatigue. Stages lasted 5 minutes. Preliminary data indicated that both groups averaged between 87% (the 9 boys) and 93 % (the 6 girls) of their respective peak oxygen consumption at the criterion referenced speeds during treadmill testing. According to the American College of Sports Medicine guidelines for healthy adults, these intensities represent the upper threshold for aerobic conditioning, and high exercise intensities can increase the risk of injury. Although the results of this study are preliminary in nature and based on a small sample size, we suggest that the criterion referenced distances (speeds) for the FYT 20-minute steady-state jog may need modification.

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Lachlan Hingley, Michael J. Macartney, Marc A. Brown, Peter L. McLennan and Gregory E. Peoples

Dietary fish oil, providing docosahexaenoic acid (DHA) modulates oxygen consumption and fatigue in animal models. However, in humans predominately supplemented with high eicosapentaenoic acid (EPA), there is no evidence of endurance performance enhancement. Therefore, this study examined if DHA-rich fish oil could improve repeated bouts of physiologically stressful cycling and a subsequent time trial in a state of fatigue. Twenty-six trained males took part in a double-blind study and were supplemented with either 2 × 1g/day soy oil, Control) or DHA-rich tuna fish oil (Nu-Mega) (FO) (560mg DHA / 140mg eicosapentaenoic acid (EPA), for 8 weeks. Maximal cycling power (3 × 6s), isometric quadriceps strength (MVC), Wingate cycling protocol (6 × 30s) and a 5min cycling time-trial were assessed at baseline and eight weeks. The Omega-3 Index was not different at baseline (Control: 4.2 ± 0.2; FO: 4.7 ± 0.2%) and increased in the FO group after eight weeks (Control: 3.9 ± 0.2; FO: 6.3 ± 0.3%, p < .01). There was no effect of DHA-rich fish oil on power output of maximal 6s cycle sprinting (Control: Pre 1100 ± 49 Post 1067 ± 51; FO: Pre 1070 ± 46 Post 1042 ± 46W), during 5min time trail (Control: Pre 267 ± 19 Post 278 ± 20; FO: Pre 253 ± 16 Post 265 ± 16 W) or maximal voluntary contraction force (Control: Pre 273 ± 19 Post 251 ± 19; FO: Pre 287 ± 17 Post 283 ± 16 Nm). Nevertheless, relative oxygen consumption was reduced the FO group during the cycling time trial (Control: -23 ± 26; FO: -154 ± 59ml O2/min/100W p < .05) suggesting improved economy of cycling. We conclude that DHA-rich fish oil, successful at elevating the Omega-3 Index, and reflective of skeletal muscle membrane incorporation, can modulate oxygen consumption during intense exercise.

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Sarah J. Willis, Jules Gellaerts, Benoît Mariani, Patrick Basset, Fabio Borrani and Grégoire P. Millet

include ventilation, core temperature, muscle metabolism, muscle fiber type, body composition, biomechanics, ground reaction force, muscle stiffness, and storage return of elastic energy. 2 RE, Cr (cost of running), and oxygen cost are sometimes interchanged in an inappropriate way. 3 Recently, it was

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Isaiah Trice and Emily M. Haymes

In this study a double-blind design was used to determine the effect of caffeine on time to exhaustion and on associated metabolic and circulatory measures. Eight male subjects ingested either caffeine (5 mg/kg body weight) or a placebo 1 hr prior to exercise at 85-90% of maximum workload. Subjects were encouraged to complete three 30-min intermittent cycling periods at 70 rpm with 5 min rest between each. The exercise was terminated when the subject failed to complete three 30-min periods or failed to maintain 70 rpm for at least 15 s consecutively. Serum free fatty acids, glycerol, blood glucose, lactate, perceived exertion, heart rate, and O2 cost were measured. The time to exhaustion was significantly longer during the caffeine trial than during the placebo trial. Serum free fatty acid levels were significantly different between trials. The decline in blood glucose levels was significantly less during the caffeine trial than during the placebo trial. There were no significant differences between trials for the other measures. It was concluded that caffeine increases time to exhaustion when trained subjects cycled intermittently at high levels of intensity.

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Øyvind Skattebo, Thomas Losnegard and Hans Kristian Stadheim

Purpose: Long-distance cross-country skiers specialize to compete in races >50 km predominantly using double poling (DP). This emphasizes the need for highly developed upper-body endurance capacities and an efficient DP technique. The aim of this study was to investigate potential effects of specialization by comparing physiological capacities and kinematics in DP between long-distance skiers and skiers competing using both techniques (skating/classic) in several competition formats (“all-round skiers”). Methods: Seven male long-distance (32 [6] y, 183 [6] cm, 76 [5] kg) and 6 all-round (25 [3] y, 181 [5] cm, 75 [6] kg) skiers at high international levels conducted submaximal workloads and an incremental test to exhaustion for determination of peak oxygen uptake (VO2peak) and time to exhaustion (TTE) in DP and running. Results: In DP and running maximal tests, TTE showed no difference between groups. However, long-distance skiers had 5–6% lower VO2peak in running (81 [5] vs 85 [3] mL·kg−1·min−1; P = .07) and DP (73 [3] vs 78 [3] mL·kg−1·min−1; P < .01) than all-round skiers. In DP, long-distance skiers displayed lower submaximal O2 cost than all-round skiers (3.8 ± 3.6%; P < .05) without any major differences in cycle times or cyclic patterns of joint angles and center of mass. Lactate concentration over a wide range of speeds (45–85% of VO2peak) did not differ between groups, even though each workload corresponded to a slightly higher percentage of VO2peak for long-distance skiers (effect size: 0.30–0.68). Conclusions: The long-distance skiers displayed lower VO2peak but compensated with lower O2 cost to perform equally with the all-round skiers on a short TTE test in DP. Furthermore, similar submaximal lactate concentration and reduced O2 cost could be beneficial in sustaining high skiing speeds in long-duration competitions.

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Nicholas Tam, Ross Tucker, Jordan Santos-Concejero, Danielle Prins and Robert P. Lamberts

spatiotemporal distance gait parameters on oxygen transport costs in trained runners. We hypothesized that better runners would display a lower oxygen cost of transport and would present with shorter ground contact times, higher stride frequencies, and muscle activation–related differences in joint stiffness

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Josu Gomez-Ezeiza, Jordan Santos-Concejero, Jon Torres-Unda, Brian Hanley and Nicholas Tam

subphases, were associated with better oxygen cost of transport in elite race walkers. 5 Although recent gait analyses in race walking have mostly assessed peaks, range of motion, and other discrete parameters of the entire gait cycle, 5 – 7 a comprehensive understanding of the role and activity of the

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Mhairi J. MacDonald, Samantha G. Fawkner, Ailsa G. Niven and David Rowe

10th and 14th minute of the 20-minute seated period using the Weir equation ( 39 ). For each walking trial (treadmill and overground), V ˙ O 2 was determined for the final 2 minutes, and subsequently converted into METs. Oxygen cost per step was calculated for each walking trial. Descriptive