Pedal Rate Research Articles

Development of a dynapod for female agricultural workers on the basis of ergonomic studies

Dynapod is a portable pedal operated power device that consists of a stand, saddle, handlebar, chain and sprockets, cranks and pedals. A person can generate four times more power by pedaling than by hand cranking. However, continuous pedaling at this rate could be done for only short periods (about 10 min). Pedaling at about half this power (90 W) could be sustained for around 60 min. Most people engaged in delivering power continuously for an hour or more would be most efficient when pedaling in the range of 50 to 70 rpm. In respect to the objective of the study, the design parameters for dynapod and the development of dynapod, a postural dynamometer for foot operated rotary power generation was designed and developed. Experiment was conducted for optimization of flywheel, pedaling rate, power output, saddle height and crank. Heart rate, oxygen consumption rate (OCR), blood pressure (BP), pulse oxygen saturation extent, rate of perceived exertion (RPE) were taken as dependent variables. The flywheel of diameter 550 mm was found to be suitable for dynapod. The optimum pedaling rate increased from minimum of about 45 rpm at 30 W to a maximum of 52 rpm at 90 W. The rate of perceived exertion (RPE) increased with increase in pedalling rate at given power output. Crank length of 180 mm and saddle height of 0.96 trochanteric height gave the minimum physiological responses. The dynapod can be successfully used as an interface between the human worker and a hand operated stationary farm equipment in pedalling mode for getting more output from the machine with less effort and fatigue.

Influence of pedalling rate on oxygen consumption during eccentric exercise

Dynamic eccentric exercise is a recent approach in terms of rehabilitation programs. These training programs are generally set on a specific workload based on a percentage of their maximal oxygen consumption (V’O2). Guidelines regarding pedaling rate can differ depending on the type of eccentric ergometer. For instance, our goal was to evaluate if these pedaling rate variations could influence (for a set work load) the level of V’O2. The hypothesis is that V’O2 will increase at a lower pedaling rate. Our goal is to evaluate the influence of pedaling rate for a set workload on oxygen consumption. We measured V’O2 of 15 healthy subjects during eccentric exercise (CPP no. AU1186) at three different amounts of work load (80-200-320 W) and two pedalling rates (50 and 80 rotations per minute [RPM]). The order was predetermined by randomization. Regarding the vastus lateralis, we recorded both the electrical activity by surface EMG and the level of tissue deoxygenation by NIRs. The data was analyzed as relative values and for each subject from the difference measured between 50 and 80 RPM. For a workload set at 200 and 320 W, V’O2 is significantly higher (P < 0.05) at 50RPM, + 94 mL.min-1 (Sd ± 139) and + 160 mL.min-1 (Sd ± 169) respectively. In addition, at 320 W, Vastus Lateralis EMG activity (quantified by root mean square) and deoxygenation level are significantly higher at 50 RPM (P < 0.05). Pedaling rate influences oxygen consumption during eccentric exercise. Lower values of V’O2 at 80 RPM vs. 50 RPM are probably due to a greater number of detachments of actin-myosin cross bridges, non ATP-dependent. A higher pedaling rate implicates a higher cycle of contraction rate and thus a higher rate of such detachments. During eccentric exercise at a set workload, pedaling rate must be taken into consideration and controlled.

Real-time pedaling rate estimation via wheel speed filtering

In this paper we propose a strategy for cycling cadence estimation from bicycle wheel speed, which does not require any physical cadence sensor. Specifically, the pedaling rate is obtained from the estimation of the employed gear ratio through a proper Kalman filtering of the processed wheel speed signal. The analysis is supported by experimental tests carried out with an instrumented bicycle.

Combined Influences of Subsystolic Regional Circulatory Occlusion and Pedal Rate on the Exercise Pressor Reflex in Healthy Adults

IntroductionThe contribution of metabolic vs mechanical stimuli related to the group III/IV afferent‐mediated exercise pressor reflex (EPR) remains incompletely understood. High pedal frequency during cycling increases type II muscle fiber recruitment and may contribute to increased anaerobically‐mediated metabolic byproduct accumulation. This may lead to an augmented rise in systolic blood pressure (SBP) and, hence, EPR in humans. Thus, we hypothesized, 1) Mean arterial pressure (MAP) will be increased during exercise with SubRCO vs without NoRCO irrespective of pedal frequency, and 2) MAP will be augmented further during exercise with SubRCO at high pedal frequencies.MethodsHealthy adults (N=13; 46% men; age 36±19 yr; BMI 24±4 kg/m2) participated in 2 study visits, each consisting of 2 sessions of fixed load (20 W) recumbent cycle ergometry with bilateral upper thigh pressure tourniquets for 8 min at a fixed pedal frequency of 35 (LOW) or 100 (HIGH) rpm (randomized). Cuffs remained at 0 mm Hg for the first 3 min (CTL), and were then randomized to 0 mm Hg (NoRCO) or 90 mm Hg (SubRCO) for the final 5 min of exercise. SBP and diastolic blood pressure (DBP) were measured via manual sphygmomanometry at the end of CTL and end‐exercise (END). MAP was calculated as (SBP + 2 * DBP)/3.ResultsThere were no between or within condition differences at CTL for MAP (P&gt;0.05). In contrast, for between SubRCO and NoRCO differences at END, MAP was increased in SubRCO vs NoRCO in both HIGH (106±12 vs 92±13 mm Hg, respectively) and LOW (94±9 vs 85±8 mm Hg, respectively) (P&lt;0.05). At END, MAP was increased in HIGH vs LOW within both SubRCO and NoRCO (P&lt;0.01). Within both NoRCO (129 ± 18 vs 117 ± 11 mm Hg) and SubRCO (125 ± 15 vs 113 ± 10 mm Hg) at CTL, SBP was increased in HIGH vs LOW, respectively (P&lt;0.01). At CTL, there were no between SBP NoRCO vs SubRCO differences in HIGH or LOW. Within SBP differences for NoRCO (134 ± 19 vs 113 ± 11 mm Hg) and SubRCO (147 ± 20 vs 127 ± 12 mm Hg) in HIGH vs LOW persisted to END, respectively (P&lt;0.01). SBP increased at END vs CTL within SubRCO for both HIGH and LOW (P&lt;0.02), but not within NoRCO (P&gt;0.05). Lastly, SBP increased in SubRCO vs NoRCO at END in both HIGH and LOW (both P&lt;0.01). There were no differences for DBP at any time point (P&gt;0.05).ConclusionThese data support our hypothesis that, independent of pedal frequency, SubRCO provokes increased MAP during fixed‐load submaximal exercise as a function of increased SBP. However, high pedal rate accompanied by SubRCO results in exaggerated SBP‐mediated increased MAP. These data contribute to an improved understanding of the stimuli that activate group III/IV afferents during exercise in humans.Support or Funding InformationNHLBI RO1 HL126638; AHA 16POST30260021

Effects of Transitioning from Un‐Occluded to Occluded Hyperbolic Submaximal Exercise on VO2 Mean Response Time and Oxygen Deficit

IntroductionAdditional oxygen uptake (VO2) beyond muscle oxygen (O2) utilization rates may coincide with exercise at or above the lactate threshold, which may be illustrated using a Phase II to III two‐exponential on‐transient VO2 kinetics model. This is expected to prolong mean response time (MRT) to VO2 steady‐state commensurate with increased O2deficit (O2def), which suggests reduced energy efficiency. Several factors may provoke metabolic acidosis during ergometry including exaggerated pedal frequency related to greater recruitment of type II muscle fibers. Also unclear is whether locomotor subsystolic regional circulatory occlusion (SubRCO), used to study group III/IV afferents during ergometry, accelerates metabolic acidosis due to influences on arterial‐to‐venous gradients. Thus, this study aimed to test the hypothesis that the transition from exercise without SubRCO to with SubRCO during fixed high rate pedaling leads to a Phase III rise in on‐transient VO2 kinetics and, hence, augmented MRT and O2def during hyperbolic submaximal exercise.MethodsHealthy adults (N = 15, 53% male; age 36 ± 17 years; BMI 24 ± 4 kg/m2) completed 2 study visits of 3 identical sessions of fixed‐load (20W) ergometry at fixed pedal rates of 35 or 100 rpm (randomized). Sessions began with 5 min of rest, followed by 3 min of exercise without SubRCO, and immediately transitioning to a 5 min period of exercise+SubRCO at 90 mm Hg bilateral‐thigh cuff inflation pressure. A metabolic system integrated with gas mass‐spectrometry was used to measure breath‐by‐breath VO2. Data were linearly interpolated to 1 sec intervals and ensemble averaged across 3 sessions/day for each participant prior to modeling. Models included: single exponential, VO2REST + A [1 − e−(t‐TD)/τ]; two exponential, VO2REST + A [1 − e−(t‐TD)/τ] + A2 [1 − e−(t‐TD2)/τ2]; O2def, [A • 8 min] − ∫ VO2dt; MRT, τ + TD; where τ = time constant; A = asymptote; TD = time delay; ∫ VO2dt = integral of actual VO2 across 8 min.ResultsSingle vs two exponential model sums of squares were similar within sessions of 35 (0.05 ± 0.03 vs 0.05 ± 0.03, P = 0.15) and 100 rpm (0.15 ± 0.07 vs 0.14 ± 0.07, P = 0.59), respectively; suggesting an absent Phase III response. Thus, MRT and O2def were derived using single exponential models beginning at t = 0. At 35 rpm, MRT = 56 ± 22 sec, and O2def = 0.36 ± 0.13 L; which differed significantly from 100 rpm, MRT = 43 ± 13 sec, and O2def = 0.70 ± 0.21 L (all P&lt;0.05).ConclusionsWhile these observations demonstrate shortened MRT but increased O2def in high versus low pedaling, these data do not suggest locomotor SubRCO provokes worsening of these parameters relating to marked dissociation between VO2 and muscle O2 utilization rates during low intensity ergometry in healthy adults. Similarly, although O2def demonstrates sensitivity to pedal rate, an absent Phase III rise in VO2 commensurate with a shortened MRT during high rate pedaling does not suggest an uncoupling of pulmonary and muscle O2 increases from early to end‐exercise in healthy adults.Support or Funding InformationNHLBI RO1 HL126638; AHA 16POST30260021

BrainCycles: Experimental Setup for the Combined Measurement of Cortical and Subcortical Activity in Parkinson's Disease Patients during Cycling.

Recently, it has been demonstrated that bicycling ability remains surprisingly preserved in Parkinson's disease (PD) patients who suffer from freezing of gait. Cycling has been also proposed as a therapeutic means of treating PD symptoms, with some preliminary success. The neural mechanisms behind these phenomena are however not yet understood. One of the reasons is that the investigations of neuronal activity during pedaling have been up to now limited to PET and fMRI studies, which restrict the temporal resolution of analysis, and to scalp EEG focused on cortical activation. However, deeper brain structures like the basal ganglia are also associated with control of voluntary motor movements like cycling and are affected by PD. Deep brain stimulation (DBS) electrodes implanted for therapy in PD patients provide rare and unique access to directly record basal ganglia activity with a very high temporal resolution. In this paper we present an experimental setup allowing combined investigation of basal ganglia local field potentials (LFPs) and scalp EEG underlying bicycling in PD patients. The main part of the setup is a bike simulator consisting of a classic Dutch-style bicycle frame mounted on a commercially available ergometer. The pedal resistance is controllable in real-time by custom software and the pedal position is continuously tracked by custom Arduino-based electronics using optical and magnetic sensors. A portable bioamplifier records the pedal position signal, the angle of the knee, and the foot pressure together with EEG, EMG, and basal ganglia LFPs. A handlebar-mounted display provides additional information for patients riding the bike simulator, including the current and target pedaling rate. In order to demonstrate the utility of the setup, example data from pilot recordings are shown. The presented experimental setup provides means to directly record basal ganglia activity not only during cycling but also during other movement tasks in patients who have undergone DBS treatment. Thus, it can facilitate studies comparing bicycling and walking, to elucidate why PD patients often retain the ability to bicycle despite severe freezing of gait. Moreover it can help clarifying the mechanism through which cycling may have therapeutic benefits.

Joint specific power production in cycling: the effect of cadence and athlete level

Introduction When increasing cadence, there is increasing knee joint contribution and decreasing hip contribution to external power [1, 2]. Increasing power output leads to a decrease in knee contribution and an increase in hip contribution [2, 3]. Low cadence (<60 rpm) interval training is a widely used training method, but previous studies have primarily focused on cadences ranging from 60 to 180 rpm, without examining the effect of low cadence on joint contribution. The present study investigates joint-specific power production in recreational and elite cyclists during cycling at a range of different cadences.  Methods Ten recreational cyclists and nine elite cyclists (Continental and ProTour-level) performed cycling bouts at seven different pedaling rates (40 to 100 and freely chosen) and four intensities. Intensities were set at 55 (Int55), 85 (Int85) and 100 % (IntLT) of predetermined lactate threshold (LT) in addition to average 20 min all out power (Int20min). All tests were performed on an indoor cycle trainer with the participants’ private road bike. Joint specific power was calculated from kinematic measurements and pedal forces using inverse dynamics  Results Mean work rate at the four different intensities were 154 W (Int55), 240 W (Int85), 282 W (IntLT) and 322 W (Int20min). The elite group had an average of 32.6 % higher LT and 38.4 % higher 20 min all out power than the recreational group. The knee joint was the major power producer at all cadences, with the exception of low cadence (<60 rpm) where the hip joint were the major power producer (fig. 1.). There was a significant main effect of cadence and intensity on the relative contribution of the hip, knee and ankle joints. At cadences above 60 rpm, increasing cadence led to a significant decrease in relative hip joint power and an increase in relative knee joint power. However, there was no effect of cadence on the relative joint contribution at cadences below 60 rpm. Relative knee joint power increased with increasing intensity, however the relative hip joint power only increased from low to moderate intensity. The elite group had significantly higher relative hip joint power and lower relative knee joint power compared to the recreational group.  Discussion and Conclusions The present study demonstrates that increasing cadence leads to a decrease in relative hip joint power and an increase in relative knee joint power, however, the effect of cadence only occurred above 60 rpm. Elite cyclists have higher relative hip joint contribution, and lower relative knee joint contribution at all cadences and intensities compared to recreational cyclists. This is to the author’s knowledge the first study to report an effect of athlete level on relative joint specific power in cycling. The findings related to the effect of cadence on joint specific power complies with earlier research [1, 2] with the exception of the effect at low cadence (<60 rpm). The lack of an effect of reducing cadence below 60 rpm may have implications for how low cadence training is carried out.

血液透析患者に対する回転数を一定にした透析中の仰臥位エルゴメータ運動介入の効果

血液透析患者に対する回転数を一定にした透析中の仰臥位エルゴメータ運動介入の効果

Hodnotenie rýchlostno-silových schopností profesionálnych hokejistov v trojročnom časovom intervale

Speed and strength may be referred to as a factor determining success in ice hockey. These abilities are developed mainly during the summer preparatory period. Upon its completion players underwent testing aimed to determine body composition, strength and anaerobic alactic abilities by performing the Wingate test. The reference sample consisted of 11 senior category ice hockey players playing for the hockey teams in NHL, KHL, and Czech and Slovak national leagues. The evaluation of changes in speed and strength between 2013 and 2015 showed gains in lower-body explosive power after a one- -year period. Compared to players playing for hockey clubs abroad, Slovak players achieved higher level of explosive power and jump height as indicated by performances in lower-body explosive power test performed both with and without countermovement. Statistical analysis showed that power increases during the initial five-second interval at lower pedaling rate on the bicycle ergometer.

The effect of aerobic exercise on dual-task gait in individuals with Parkinson's disease

Background/Aims: Dual tasking exacerbates gait deficits in people with Parkinson's disease. This pilot study aimed to examine the effect of aerobic exercise on dual-task gait in individuals with Parkinson's disease and begin to identify the impact of volitional pedal rate. Methods: Twenty people with Parkinson's disease were recruited and tested at baseline, post-intervention, and follow-up for motor (Unified Parkinson's Disease Rating Scale) and cognitive function (Repeatable Battery for the Assessment of Neuropsychological Status) and dual-task gait (Time Up and Go) conditions (manual and cognitive). A 12-week aerobic exercise intervention of cycle ergometry was carried out three times a week for 60 minutes each session. To assess our intervention, separate repeated measures of analysis of variance were conducted. As determined a priori, to assess the impact of volitional pedal rate, participants were divided after the intervention into a high-pedal rate group (&gt;60 rpm) and a low-pedal rate group (≤60 rpm) based upon average maximal pedal rate throughout the intervention and analysed with the Mann Whitney U test and Related Samples Wilcoxon Signed Rank Test. Findings: Overall, motor function (P=0.580), cognitive function (P=0.077), and motor-cognitive interplay (P=0.168) did not improve after aerobic exercise. However, pedal rate groups were different for TUGmanual and TUGcognitive, but not on motor or cognitive function. Only low-pedal rate group improved over time (P=0.028 on TUGmanual) and demonstrated reduced dual task cost after the aerobic exercise (&gt;Minimal Detectible Change of 18.1%). Conclusions: Though the low-pedal rate group experienced greater motor-cognitive interference, persons who pedalled at the slower rate demonstrated the most improvement in dual-task activities.

Increase in Maximal Cycling Power With Acute Dietary Nitrate Supplementation.

This study determined whether NO3- supplementation could acutely enhance maximal power in trained athletes. In this double-blind, crossover study, 13 trained athletes performed maximal inertial-load cycling trials (3-4 s) immediately before (PRE) and after (POST) consuming either NO3-rich (NO3) or NO3-depleted (PLA) BRJ to assess acute changes (ie, within the same day) in maximal power (PMAX) and optimal pedaling rate (RPMopt). Participants also performed maximal isokinetic cycling (30 s) to assess performance differences after supplementation. 2 x 2 repeated-measures ANOVA indicated a greater increase in PMAX from PRE to POST NO3 (PRE 1160 ± 301 W to POST 1229 ± 317 W) than with PLA (PRE 1191 ± 298 W to POST 1213 ± 300 W) (P = .009; ηp2 = 0.45). A paired t-test verified a greater relative change in PMAX after NO3 (6.0% ± 2.6%) than with PLA (2.0% ± 3.8%) (P = .014; d = 1.21). RPMopt remained unchanged from PRE (123 ± 14 rpm) to POST PLA (122 ± 14 rpm) but increased from PRE (120 ± 14 rpm) to POST NO3 (127 ± 13 rpm) (P = .043; ηp2 = 0.30). There was no relative change in RPMopt after PLA (-0.3% ± 4.1%), but there was an increase after NO3 (6.5% ± 11.4%) (P = .049; d = 0.79). No differences were observed between the 30-s isokinetic trials. Acute NO3- supplementation can enhance maximal muscle power in trained athletes. These findings may particularly benefit power-sport athletes who perform brief explosive actions.

Energy Expenditure Overestimation Bias in Elliptical Trainer Machine

Elliptical trainers are a common mode of aerobic exercise in recreationally active populations. Those with a weight loss goal might rely upon the energy expenditure (EE) estimation that many elliptical brands provide to keep track of calories (kcals) burned and make nutritional decisions. For this reason, it is important to evaluate the accuracy of the algorithms used by elliptical trainers to estimate EE. PURPOSE:To compare EE estimates by a common brand of elliptical trainer to that measured using open circuit spirometry, at different combinations of resistance and pedal speed. METHODS:Twenty subjects (10 male, 10 female; 34 ± 12 yr; 175.3 ± 10.7 cm; 77.1 ± 14.1 kg) consented to participate. Each completed three 15-min bouts of elliptical exercise on the same elliptical trainer, with at least 24 hr between exercise bouts. Pedal rates were held constant throughout each bout at 50, 60, or 70 RPM, and resistance was increased incrementally every 5 min from level 5 to 10 to 15. The different cadences were completed in a randomized order between participants. Expired gases were collected continuously throughout the 15 min. Heart rate, distance (mi), and EE from the elliptical readout were recorded every 1 min. RPE was collected twice per resistance level. A two-tailed paired samples t-test was used to compare elliptical EE to measured EE. A linear regression model was used to evaluate the ability of the elliptical EE to predict measured EE. Significance for all statistical measures was held at an alpha level of 0.05. RESULTS:The difference between EE estimates from the elliptical and measured VO2 was significant (p<0.0001), with the elliptical machine overestimating EE during a 15 minute session by an average of 10.21 kcals. Measured EE in kcals as derived from open circuit spirometry was significantly predicted by elliptical EE according to the equation: Measured EE = 0.95*(Elliptical EE) - 3.161 CONCLUSIONS:The elliptical trainer used demonstrated a bias to overestimate EE. This should be taken into account by health/fitness professionals using these estimations to program for clients. There may be some variation in the EE correction regression depending on elliptical model, and proper machine calibration should be ensured.

Oral Essential Amino Acids, Sprint Exercise And Collagens In Human Skeletal Muscle

PURPOSE: To investigate the effects of oral ingestion of essential amino acids (EAA exercise on the global gene expression in skeletal muscle after sprint exercise. METHODS: Twelve healthy physically active subjects (age 20-30 years) performed three 30-s cycle sprints with maximal voluntary pedaling rate on a mechanically braked cycle ergometer with 20 min rest between the sprints. The braking force was set at 0.75 N/kg body weight. The subjects consumed either EAA + maltodextrin solution or flavored water (placebo) in a randomized order. A post exercise biopsy (m. vastus lateralis) was taken 200 minutes after the last cycle sprint. RNA was isolated from the frozen muscle biopsies using TRIzol protocol. Purification was executed using RNeasy Mini Kit (Qiagen). The RNA concentration was determined using the NanoDrop (Thermo Fischer Scientific) and quality assessed by Agilent (Agilent Technologies). The Affymetrix Gene Chip Whole Transcript (WT) Sense Target Labeling Assay Manual was used for complementary DNA (cDNA) generation, hybridization and array processing (GeneChip® Human Transcriptome Array 2.0). Differentially expressed genes in response to EEA in combination with the sprint exercise were analyzed using the Ingenuity Pathways Analysis (IPA) software application. To validate microarray data total RNA was reverse transcribed using random hexamer primers. Real-time PCR was applied to measure mRNA expression using RPS18 as reference to correct for potential variation in RNA loading. RESULTS: The IPA Network analysis showed an enrichment of activated genes related to collagen metabolism. Some of the genes in the pathway analysis were validated by the PCR analysis. The expression of COL15A1, COL1A1, COL2A1 and BGN was higher in the EEA condition compared to the placebo condition (P<0.05). CONCLUSION: Oral ingestion of EAA after sprint exercise increases expression of genes related to collagen metabolism. The functional role of an activation of collagen metabolism is not known, although it could be speculated that an altered collagen metabolism reflects an extracellular remodeling after exercise and that this process is enhanced by oral ingestion of EEA. SUPPORT: The study was supported by grants from the Swedish National Center for Research in Sports.

Effect Of Training Under Hyperoxia On Exercise Performance And Aerobic Capacity In Trained Cyclists

Some previous studies suggested that trained athletes can perform exercise at high power outputs and long duration during inspiration of a hyperoxic gas mixture, which would inhibit the decrease in arterial oxygen saturation (SpO2) levels during intense exercise. Training under hyperoxia could increase aerobic capacity, and thus improve exercise performance in trained athletes. PURPOSE: This study aimed to determine the effect of training under hyperoxia on exercise performance and aerobic capacity in trained cyclists. METHODS: Six male trained cyclists (age: 21.3 ± 1.9 yr, height: 168.6 ± 5.5 cm, weight: 59.7 ± 9.0 kg) performed training under hyperoxia. Before the training periods (pre-training), the subjects performed an incremental exercise test to exhaustion in which the work rate at initiation was 120 W for 3 min. The work rate was then increased as a step function by 40 W every 3 min at a pedal rate of 90 rpm to determine the workload corresponding to the maximal oxygen uptake (VO2max) and work rate max (WRmax) by using a bicycle ergometer. VO2max was determined by calculating the average of the breath–by–breath data over 30-s intervals during the incremental test. All the subjects underwent training under hyperoxia on 3 days per week for a 4-weeks period. The training protocol consisted of 5 repetitions of intense exercise at 3–min intervals. The intensity of the intense exercise was 90–100% WRmax. The duration of the intense exercise was 3 min in sets of 1–4, and the subjects cycled to voluntary exhaustion in 5 sets. All the subjects completed the training under conditions of hyperoxic gas mixture (36.1–37.2% O2). They also performed the incremental exercise test 3–6 days after the training periods (post-training). RESULTS: The time required by the subjects to perform the incremental exercise test in the post-training period was significantly longer than that required in the pre-training period (16.69 ± 1.64 min vs. 15.81 ± 2.22 min; p = 0.022). There were no statistically significant differences in VO2max between the post-training period and the pre-training period (57.2 ± 6.0 ml min-1 vs. 56.2 ± 6.6 ml min-1). CONCLUSION: Our results showed that submaximal training with inspiration of a hyperoxic gas mixture for 4 weeks improves exercise performance in trained cyclists.

The Effect of Pedaling Frequency and Stretching on FAT/CHO Crossover Point

An acute bout of stretching will decrease muscular strength, power and endurance, which could possibly be due to an increased inhibition of motor neurons. Animal research has well established that slow motor neurons are activated first and are more oxidative. Unfortunately, research has been inconclusive as to whether the stretch induced inactivation of motor units also has speed specificity like that of activation; therefore it is possible a stretch induced inactivation would alter the amounts of carbohydrates(CHO) and fat(FAT) used at slower speeds. PURPOSE: To determine if stretching changes substrate utilization during exercise, yielding different FAT/CHO crossover points. METHODS: 15 Men and women (age 22±4.5y; mean±SD) college aged participants (VO2Max= 31.9±5.5mL·kg-1·min-1) were recruited for the study. Each participant was tested on a Velotron® cycle ergometer with and without pre-cycling stretching. Stretching consisted of five different passive static stretches which were held for fifteen seconds and repeated three times. An assistive stretching session followed with the same five stretches held for fifteen seconds and repeated three times. The non-stretched condition consisted of ten minutes of quiet sitting. Following the stretch treatment participants pedaled at 50 revolutions per minute (RPM) for 6 minute stages. The exercise workload started at 15 watts(W) and increased by 15W until an RER of 0.95 was reached, ensuring the crossover point (RER = 0.85) had been surpassed. RESULTS: Mean VO2 (L/min) corresponding to the crossover point was 0.51±0.37 L/min and 0.58±0.51 L/min for stretching and non-stretching conditions at 50 RPM, respectively (p>0.5). The results revealed no difference (P>0.5) in the crossover point, demonstrating no difference in substrate utilization with and without stretching prior to cycling at a slower pedal rate. CONCLUSION: These data suggest that prior static and active stretching does not elicit a stretch induced inactivation that can alter substrate usage.

Effects of Exhaustive Aerobic Exercise on Tryptophan-Kynurenine Metabolism in Trained Athletes.

Exhaustive exercise can cause a transient depression of immune function. Data indicate significant effects of immune activation cascades on the biochemistry of monoamines and amino acids such as tryptophan. Tryptophan can be metabolized through different pathways, a major route being the kynurenine pathway, which is often systemically up-regulated when the immune response is activated. The present study was undertaken to examine the effect of exhaustive aerobic exercise on biomarkers of immune activation and tryptophan metabolism in trained athletes. After a standardized breakfast 2 h prior to exercise, 33 trained athletes (17 women, 16 men) performed an incremental cycle ergometer exercise test at 60 rpm until exhaustion. After a 20 min rest phase, the participants performed a 20 min maximal time-trial on a cycle ergometer (RBM Cyclus 2, Germany). During the test, cyclists were strongly encouraged to choose a maximal pedalling rate that could be maintained for the respective test duration. Serum concentrations of amino acids tryptophan, kynurenine, phenylalanine, and tyrosine were determined by HPLC and immune system biomarker neopterin by ELISA at rest and immediately post exercise. Intense exercise was associated with a strong increase in neopterin concentrations (p<0.001), indicating increased immune activation following intense exercise. Exhaustive exercise significantly reduced tryptophan concentrations by 12% (p<0.001) and increased kynurenine levels by 6% (p = 0.022). Also phenylalanine to tyrosine ratios were lower after exercise as compared with baseline (p<0.001). The kynurenine to tryptophan ratio correlated with neopterin (r = 0.560, p<0.01). Thus, increased tryptophan catabolism by indoleamine 2,3-dioxygenase appears likely. Peak oxygen uptake correlated with baseline tryptophan and kynurenine concentrations (r = 0.562 and r = 0.511, respectively, both p<0.01). Findings demonstrate that exhaustive aerobic exercise is associated with increased immune activation and alterations in monoamine metabolism in trained athletes which may play a role in the regulation of mood and cognitive processes.

Timing of carbohydrate ingestion did not affect inflammatory response and exercise performance during prolonged intermittent running.

BackgroundCarbohydrate ingestion during exercise is known to attenuate exercise-induced elevation of plasma IL-6 concentration. However, the influence of timing of carbohydrate ingestion remains unclear.PurposeThe present study investigated the influence of different timing of carbohydrate ingestion during a simulated soccer game on exercise performance, metabolic and inflammatory responses.MethodsSeven active males performed 3 exercise trials in a randomized order. The exercise consisted of two consecutive bouts of 45 min running (4–16 km/h), separated with 15 min rest period between bouts. The subjects ingested carbohydrate gel (1.0 g/kg) immediately before the first bout of exercise (ONE), immediately before first and second bouts of exercise (0.5 g/kg for each ingestion) (TWO) or placebo immediately before exercise (PLA) Time course changes of maximal jump height, peak power output during 6-s maximal pedaling, perceived fatigue and heart rate (HR) were monitored. Blood samples were also drawn to determine blood glucose, serum insulin, free fatty acid (FFA), myoglobin (Mb), creatine kinase (CK) and plasma IL-6 concentrations.ResultsBlood glucose and serum insulin concentrations were significantly higher in the ONE trial after first bout of 45 min exercise compared with PLA trial (P < 0.05), while serum FFA concentration was significantly elevated in PLA compared with ONE and TWO trials after second bout of exercise (P < 0.05). However, changes of jump height, peak power output during 6-s maximal pedaling, perceived fatigue, HR, or indirect muscle damage (Mb, CK) and inflammatory (IL-6) markers were not significantly different among three trials (P > 0.05).ConclusionsThe timing of carbohydrate ingestion did not affect exercise performance, exercise-induced muscle damage or inflammatory response during a simulated soccer game.

Effect of Locomotor Respiratory Coupling Induced by Cortical Oxygenated Hemoglobin Levels During Cycle Ergometer Exercise of Light Intensity.

This study aimed to clarify the effects of locomotor-respiratory coupling (LRC) induced by light load cycle ergometer exercise on oxygenated hemoglobin (O2Hb) in the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and sensorimotor cortex (SMC). The participants were 15 young healthy adults (9 men and 6 women, mean age: 23.1 ± 1.8 (SEM) years). We conducted a task in both LRC-inducing and LRC-non-inducing conditions for all participants. O2Hb was measured using near-infrared spectroscopy. The LRC frequency ratio during induction was 2:1; pedaling rate, 50 rpm; and intensity of load, 30 % peak volume of oxygen uptake. The test protocol included a 3-min rest prior to exercise, steady loading motion for 10 min, and 10-min rest post exercise (a total of 23 min). In the measurement of O2Hb, we focused on the DLPFC, SMA, and SMC. The LRC frequency was significantly higher in the LRC-inducing condition (p < 0.05). O2Hb during exercise was significantly lower in the DLPFC and SMA, under the LRC-inducing condition (p < 0.05). The study revealed that even light load could induce LRC and that O2Hb in the DLPFC and SMA decreases during exercise via LRC induction.

Immersible ergocycle prescription as a function of relative exercise intensity

PurposeThe purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake (%VO2max), percentage of maximal heart rate (%HRmax), %VO2 reserve (%VO2R), and %HR reserve (%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle (IE) and to propose a prediction equation to estimate oxygen consumption (VO2) based on IE pedaling rate (rpm) for an individualized exercise training prescription. MethodsThirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle (DE) at equal external power output (Pext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO2 was measured with a portable gas analyzer (COSMED K4b2) during both incremental tests. On IE and DE, %VO2R, %HRmax, and %HRR at equal Pext did not differ (p > 0.05). ResultsThe %HRR vs. %VO2R regression for both IE and DE did not differ from the identity line %VO2R IE = 0.99 × HRR IE (%) + 0.01 (r2 = 0.91, SEE = 11%); %VO2R DE = 0.94 × HRR DE (%) + 0.01 (r2 = 0.94, SEE = 8%). Similar mean values for %HRmax, %VO2R, and %HRR at equal Pext were observed on IE and DE. Predicted VO2 obtained according to rpm on IE is represented by: VO2 (L/min) = 0.000542 × rpm2 − 0.026 × rpm + 0.739 (r = 0.91, SEE = 0.319 L/min). ConclusionThe %HRR–%VO2R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE.

Design and Development of a Smart Exercise Bike for Motor Rehabilitation in Individuals with Parkinson's Disease.

Recent studies in rehabilitation of Parkinson's disease (PD) have shown that cycling on a tandem bike at a high pedaling rate can reduce the symptoms of the disease. In this research, a smart motorized bicycle has been designed and built for assisting Parkinson's patients with exercise to improve motor function. The exercise bike can accurately control the rider's experience at an accelerated pedaling rate while capturing real-time test data. Here, the design and development of the electronics and hardware as well as the software and control algorithms are presented. Two control algorithms have been developed for the bike; one that implements an inertia load (static mode) and one that implements a speed reference (dynamic mode). In static mode the bike operates as a regular exercise bike with programmable resistance (load) that captures and records the required signals such as heart rate, cadence and power. In dynamic mode the bike operates at a user-selected speed (cadence) with programmable variability in speed that has been shown to be essential to achieving the desired motor performance benefits for PD patients. In addition, the flexible and extensible design of the bike permits readily changing the control algorithm and incorporating additional I/O as needed to provide a wide range of riding experiences. Furthermore, the network-enabled controller provides remote access to bike data during a riding session.