No description available.

Objective. This study investigated the effect of cycling position (upright vs. recumbent) and seat position on the oxygen cost of cycling. / Experimental design. A two-factor ANOVA with repeated measures was used to examine the effect of cycling position (Monark 814E, Lifecycle 9100 R, and Lifecycle 9500 RHR ergometers) and seat position (optimum and +/-1 setting) on VO2 and HR. / Participants. Subjects were 10 male physical education students (age = 24 +/- 2.1 years, height = 178.8 +/- 4.8 cm, weight = 76.2 +/- 7.8 kg). / Interventions. Each subject was tested at three 5-minute workloads (55, 137, and 186 Watts) in a random order on the three ergometers. These workloads corresponded with manual settings of 1, 3, and 5 on the Lifecycle ergometers. The cycling protocols for the Lifecycle ergometers were performed with the seat set at 107% of the symphysis pubis measurement and at seat positions of +/-1 setting from the so-called "optimum" setting. / Measures. Physiological response was assessed by continuously monitoring VO2 and HR. / Results. At the optimum seat setting, the VO2 was significantly higher at the three workloads on the Monark compared to both Lifecycle ergometers. Seat positions of +/-1 setting from the recommended setting did not affect VO2. The HR response was non-significant for cycling position and seat position. / Conclusions. The results indicate that the Lifecycle ergometers (9100 R and 9500 RHR) underestimate oxygen consumption and indirectly underestimate energy expenditure. Seat positions of +/-1 setting from the recommended setting on the Lifecycle ergometers did not affect the VO 2.

The purpose of this study was to examine the effects off revolution rate (i.e. gear ratio) on cycling efficiency and the energy cost of performance. A group of five trained cyclists performed ergometerr rides at either 60, 90, or 120 rpm and a constant absolute workload. Energy expenditure was determined during each minute of rest,-exercise, and recovery. Gross and net work efficiencies were calculated using several computational methods. Results showed that energy input increased as the rate of cycling increased. Gross and net resting baseline efficiencies decreased and net free wheeling baseline efficiency remained constant with increasing rpm. The increased energy demand with increased rpm was attributed to the increased cost of moving the legs and not to overcoming the resistance. It was concluded that the fastest performance ..s achieved when the energy demand is the greatest for the force exerted on the pedals and the oxygen debt could be tolerated for the duration of the race. Within the limitations of the study, at a constant work output the greatest muscular efficiency was achieved at low revolution rates. Although the net free wheeling efficiencies remained unchanged with increasing rpm, in practical terms these values did not reflect the total energy cost to the rider.

No description available.

PowercranksTM are a device that enables the user to cycle with each leg acting independently of the other. This type of cycling forces the rider to actively pull up with the hip and knee flexors throughout the recovery phase of the pedaling cycle. While the metabolic benefits of training with PowercranksTM are known, no research has investigated what, if any, strength benefits result from training. The purpose of this study was to examine how strength, submaximal oxygen consumption, hear rate, gross efficiency, and muscle activation were affected by 6 weeks of PowercranksTM training, compared to a traditional cycling training. A total of 1 1 recreationally trained adult subjects (5 males, 6 females) were randomly placed into either the PowercranksTM group (PC) or regular cranks (RC) group. Subjects trained 3 days per week following a progressive interval protocol for 6 weeks. Prior to and following training, subjects were measured for peak isokinetic knee and hip flexion/extension strength, timing of muscular contractions, and submaximal VO2, heart rate, and gross efficiency. A MANOVA for strength values pre-post were not significant. However, large effect sizes implied that there were increases in knee and hip flexion for the PC group (d =1.00,1.63, respectively). Heart rate was found to be significant at all 4 time points (p = 0.001, 0.011, 0.001, 0.000 for time points 1-4, respectively). MANOVAs for VO2 and GE did not yield significant results. Muscular timing was also unchanged as a result of training. While the PowercranksTM did not have an effect on VO2 and GE in untrained subjects, HR decreased, suggesting an aerobic benefit. The possible strength benefits in untrained subjects resulting from PowercrankTM training could prove beneficial for individuals looking to recover from injury. / School of Physical Education, Sport, and Exercise Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

No description available.

M.Tech. (Chiropractic) / Background: Sport as a whole, and especially cycling, has become a major part of the majority of the world population’s daily lives. There have been several studies done to determine the effects of chiropractic treatment on individual muscle groups (Maris, 2003; Sher, 2002). However, very few studies have been done to look at the combined effects of chiropractic on the performance of specific sports. Objective: To investigate the effects of chiropractic manipulative therapy on power output over a one kilometer distance in asymptomatic amateur cyclists. Method: The study consisted of 30 participants. All participants accepted had to meet the inclusion criteria. They were equally and randomly allocated into 3 groups. Group 1 received chiropractic therapy of the lumbar spine. Group 2 received chiropractic therapy of the sacroiliac joint whilst participants in Group 3 received no immediate intervention as they were the control group. Participants in Group 1 and 2 were motion palpated to determine the level of spinal dysfunction. All three groups then cycled on a stationary bike for a one kilometer sprint. Allocated treatment for Group 1 and Group 2 then followed, with Group 3 receiving no intervention. Objective measurements consisted of average power output as well as time over the one kilometer distance from start to finish. Results: Both test groups showed significant clinical as well as statistical improvement over the six week clinical study period. This means that as the average power output measurements increased, the time decreased for both Group 1 and Group 2. Although there were some degree of increased power output and decrease in time of Group 3, it was not significant enough to say that they had increased performance. Conclusion: Chiropractic manipulative therapy did cause an increase in average power output in asymptomatic amateur cyclists over a one kilometer distance.

Background: As variable-geared, elliptical Rotor Q-rings may improve pedal dynamics by reducing the effect of the "dead spot" in the pedaling action and altering the mechanical leverage, use of these chain rings is currently gaining popularity among competitive amateur and professional cyclists. There are, however, no randomized, controlled, published studies examining the physiological effect of using Rotor Q-rings vs. standard circular chain rings. In addition, no previous studies comparing circular and noncircular chain rings have included analysis of the markers of exercise induced muscle damage. Aim: This work was designed to compare physiological response to an incremental cycling protocol when using Rotor Q-rings (QR) with an eccentricity ratio of 1.10 and 74° default setting, to that obtained when normal, circular chain rings (NR) are used. Methods: Twelve trained amateur cyclists (age: 40.67 ± 7.53 years) performed two incremental tests to exhaustion on their own bicycles in a controlled laboratory environment. The subjects were randomized to QR and NR trials which took place seven days apart, within a cross-over design. The type of chain ring attached to the cycle (QR vs. NR) was blinded from the participant. After an eight-minute warm-up at 130 W, the power output was increased by 30 W on the minute. During each trial, heart rate, VE, V02 were measured continuously and RPE and blood lactate concentration were measured during the last 15 seconds of each workload. Ventilatory and blood lactate turn- points were determined from serial VE and blood lactate concentrations. Serum lactate dehydrogenase (LDH) concentration was measured before and immediately after each trial. A numerical pain rating scale was used to assess post exercise leg muscle and knee joint soreness 24hr post trial. Results: There was no statistically significant difference (p > 0.05) in mean peak power output (380 ± 29.0 W vs. 385 ± 31.8 W), mean power (194.9 ± 12.7 W vs. 197.2 ± 16.7 W), mean distance covered (9.02 ± 1.29 km vs. 8.89 ± 1.84 km) during the QR and NR trials, respectively. There were no statistically significant differences between trials in submaximal and maximal V02, VE or RPE, and ventilatory or lactate turnpoints (p > 0.05). Knee pain and leg muscle soreness as well as and increment in serum LDH levels did also not differ significantly following the two trials (p > 0.05). The difference in peak blood lactate concentrations (12.62 mmol. £"' ± 2.15 on QR vs. 13.84 mmol. £"' ± 1.68 on NR), however, reached borderline significance (p = 0.055). Conclusion: Despite the popularity of non-circular chain rings and the apparent mechanical advantage derived from their use, the findings of this study were unable to provide support for significant physiological advantages when using Rotor Q-rings with an eccentricity ratio of 1.10 and 74° default setting, during an incremental cycling test to exhaustion. While the borderline significance of the lower mean maximal blood lactate concentration following the Q-ring trial requires confirmation in a larger study, the possible roles of training, higher eccentricity ratios and different orientations of the crank to the chain ring in eliciting a physiological advantage, require further investigation. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, 2008.

The goal of the present investigation was to evaluate the role of the pulmonary diffusion capacity (as measured by DLco) in relation to exercise-induced hypoxemia in elite athletes working at near maximal exercise intensities. Twenty-four elite cyclists were submitted to a direct measurement of VO$ sb2$ max on cycle ergometer which permitted classification into one of two groups. "Desaturaters" (N = 13) if oxyhemoglobin saturation (SaO$ sb2$%), as determined by finger oxymetry, fell below 91% or "non-desaturaters" if SaO$ sb2$% remained above 91%. Subsequent determinations of the transfer capacity for CO (DLco) were made using a 3 second breath-hold technique (Gould 2400/2450), at rest as well as at 60% and 90% of previously determined VO$ sb2$ max ($>$4.0 1/min). The results show an increase in DLco from rest to the first exercise intensity (desat: 41.7 $ pm$ 5.7 to 55.1 $ pm$ 4.7; non-desat: 41.1 $ pm$ 5.8 to 57.2 $ pm$ 6.9 mlsCO/mmHg/min) without much further increase to the maximal workload (desat: 61.0 $ pm$ 6.0; non-desat: 61.4 $ pm$ 9.5 mls CO/mmHg/min). No significant differences in DLco were found between the two groups at rest or either of the two exercise intensities. Significant differences between the desat and non-desat groups were found for FVC, post-exercise FEF$ sb{25-75 %}$, and VE/VO$ sb2$. / The present results are in agreement with previous reports showing arterial desaturation in 50% of highly-trained subjects when VO$ sb2$ max $>$4.0 1/min. The present investigation cannot clearly establish the role of DLco in this response. (Abstract shortened by UMI.)