Design of an eccentric recumbent ergometer to elicit delayed onset muscle soreness.

INTRODUCTION: Our objective was to design an eccentric bicycle design to elicit delayed onset muscle soreness (DOMS). METHODS: To assess the bicycle designs' ability to elicit DOMS, fourteen, recreationally active, males performed five-minutes of eccentric bicycling at 50% of their individualized power determined from a modified six-second Wingate test. Outcome measures to assess DOMS included the Likert pain scale, creatine kinase, lactate blood concentration, and pressure algometry detection evaluated at four time points (baseline (before the eccentric bicycling), immediate post, 24 hours post, and 48 hours post). RESULTS: The Likert pain scale was different (F = 75.88, p < 0.001) at baseline (0.14 ± 0.36) and immediate post (0.21 ± 0.43), compared to 24 hours post (3.07 ± 0.83), and 48 hours post (2.93 ± 1.07). No changes were reported for creatine kinase (F = 0.7167, p = 0.475), lactate blood concentration (F = 2.313, p = 0.107), or pressure algometry detection. CONCLUSIONS: To understand mechanisms of DOMS, there is a need for a consistent, reliable method for producing DOMS. Our eccentric bicycle design and protocol offers an alternative approach to previous eccentric ergometer designs - demonstrating the potential to elicit DOMS in one, five-minute session.

Knee extension with blood flow restriction: Impact of cuff pressure on hemodynamics.

INTRODUCTION: Blood flow restriction (BFR) exercise has emerged as a method of increasing muscle size and strength with low intensity resistance training. While the cuff pressures used during BFR are typically a percentage of resting arterial occlusion pressure (AOP), the impact these cuff pressures have on blood flow during lower body exercise is unknown. PURPOSE: To determine how various cuff pressures impact blood flow and tissue perfusion during exercise. METHODS: Eleven healthy male participants completed four sets of knee extension (30 reps per set at 30% max torque) with 0%, 60%, 80%, and 100% of arterial occlusion pressure (AOP) was applied to the proximal portion of the thigh. Femoral artery blood flow, tissue oxygenation, and central hemodynamics were continuously recorded before, during, and after exercise. Electromyography (EMG) amplitude was recorded from the vastus lateralis during exercise. RESULTS: Blood flow increased during exercise compared to rest across all cuff pressures (p < 0.001), however compared to 0%, the absolute blood flow was reduced by 34 ± 17%, 45 ± 22%, and 72 ± 19% for 60, 80, and 100% AOP, respectively. Furthermore, each cuff pressure resulted in similar relative changes in blood flow before, during, and after exercise. During exercise, tissue saturation index (TSI) decreased as cuff pressure increased (p ≤ 0.005) with the exception of 80 to 100% AOP. Deoxyhemoglobin increased (p ≤ 0.001) with cuff pressure. CONCLUSION: Our data indicate that while BFR knee extension elicits an absolute hyperemic response at cuff pressures up to 100% resting AOP, the relative reductions in blood flow are consistent across rest, exercise and recovery.

Non-Motor Symptoms after One Week of High Cadence Cycling in Parkinson's Disease.

The objective was to investigate if high cadence cycling altered non-motor cognition and depression symptoms in individuals with Parkinson's disease (PD) and whether exercise responses were influenced by brain-derived neurotrophic factor (BDNF) Val66Met polymorphism. Individuals with idiopathic PD who were ≥50 years old and free of surgical procedures for PD were recruited. Participants were assigned to either a cycling (n = 20) or control (n = 15) group. The cycling group completed three sessions of high cadence cycling on a custom motorized stationary ergometer. The primary outcome was cognition (attention, executive function, and emotion recognition were assessed via WebNeuro® and global cognition via Montreal Cognitive Assessment). Depression symptoms were assessed via Beck Depression Inventory-II. There was a main effect of time for emotional recognition (p = 0.048), but there were no other changes in cognition or depression symptoms. Regardless of intervention or Val66Met polymorphism, high cadence cycling does not alter cognition or depression symptoms after three sessions in one week.

Limb blood flow and tissue perfusion during exercise with blood flow restriction.

INTRODUCTION: Exercise with blood flow restriction (BFR) is emerging as an effective modality for improving muscular function in clinical and athletic populations. Selection of cuff pressure is critical because it should maximize metabolic stress without completely occluding blood flow or compromising user safety. It is unknown how cuff pressures determined at rest influence blood flow hemodynamics during exercise. PURPOSE: We evaluated changes in blood flow and tissue perfusion before, during, and after exercise with BFR. METHODS: Ten males performed rhythmic handgrip exercise (30 contractions, 30% MVC) at 0%, 60%, 80%, 100%, and 120% of limb occlusion pressure (LOP). Brachial artery blood flow and tissue saturation were assessed using Doppler ultrasound and near-infrared spectroscopy, respectively. RESULTS: At rest blood flow generally decreased with increased pressure (0% > 60% ≈ 80% > 100% ≈ 120% LOP). During 60% and 80% LOP conditions, blood flow increased during exercise from rest and decreased after exercise (all P < 0.05). Compared to 0% LOP, relative blood flow at 60% and 80% LOP decreased by 22-47% at rest, 22-48% during exercise, and 52-71% after exercise (all P < 0.05). Increased LOP decreased tissue saturation during exercise with BFR (P < 0.05). Heart rate, mean arterial pressure, and cardiac output did not differ across LOP. CONCLUSION: At pressures below LOP the cardiovascular system overcame the external pressure and increased blood flow to exercising muscles. Relative reductions in blood flow at rest were similar to those during exercise. Thus, the relative occlusion measured at rest approximated the degree of occlusion during exercise. Moderate cuff pressures increased metabolic stress without completely occluding blood flow.

Lower Aerobic Endurance Linked to History of Depression in Multiple Sclerosis: Preliminary Observations.

BACKGROUND: Despite the demonstrated benefits of exercise in multiple sclerosis (MS), this population shows low rates of physical activity. Understanding barriers to exercise in persons with MS is important. The current study examined the relationship between lifetime history of depression, current depressive symptoms, and aerobic endurance in persons with relapsing-remitting MS to determine whether depression might be one such barrier. METHODS: Thirty-one participants with relapsing-remitting MS self-reported current depressive symptoms and history of depression. Aerobic endurance was assessed via 2-Minute Step Test. RESULTS: Linear regression demonstrated that lifetime history of depression predicted lower aerobic fitness whereas current depressive symptoms did not. CONCLUSIONS: Findings suggest a possible role of lifetime depression as a barrier to exercise in MS and highlight the importance of effective treatment of depression in this population to reduce its potential impact on exercise adherence.

Passive limb movement intervals results in repeated hyperemic responses in those with paraplegia.

STUDY DESIGN: Repeated measures. OBJECTIVES: Reports suggest passive limb movement (PLM) could be used as a therapy to increase blood flow and tissue perfusion in the paralyzed lower limbs of those with spinal cord injuries. However, the hyperemic response to PLM appears to be transient, lasting only 30-45 s despite continued limb movement. The purpose of this investigation was to determine whether the hyperemic response is repeatable across multiple short bouts of passive limb movement. SETTING: Cleveland Veterans Affairs Medical Center. METHODS: Nine individuals with paraplegia 46 ± 6 years of age, 17 ± 12 years post injury (range: 3-33 years) with complete T3-T11 injuries were subject to 5 × 1 min bouts of passive knee extension/flexion at 1 Hz with a 1 min recovery period between each bout. Heart rate (HR), mean arterial pressure (MAP), femoral artery blood flow (FABF), skin blood flow (SBF), and tissue perfusion in the lower limb were recorded during baseline and throughout each bout of PLM. RESULTS: Despite no increase in HR (p ≥ 0.8) or MAP (p ≥ 0.40) across all four bouts of PLM, the average increase in FABF during each bout ranged from 71 ± 87% to 88 ± 93% greater than baseline (p ≤ 0.043). SBF also increased between 465 ± 302% and 582 ± 309% across the five bouts of PLM (p ≤ 0.005). CONCLUSIONS: Repeated bouts of PLM in those with SCI while in an upright position resulted in a robust and steady increase in FABF and SBF which could have implications for improving vascular health and tissue perfusion in the lower limbs of those with paraplegia.

Pilot physiology, cognition and flight performance during flight simulation exposed to a 3810-m hypoxic condition.

BACKGROUND: Hypoxia is a physiological state defined as a reduction in the distribution of oxygen to the tissues of the body. It has been considered a major factor in aviation safety worldwide because of its potential for pilot disorientation. Pilots are able to operate aircrafts up to 3810 m without the use of supplemental oxygen and may exhibit symptoms associated with hypoxia. OBJECTIVE: To determine the effects of 3810 m on physiology, cognition and performance in pilots during a flight simulation. METHODS: Ten healthy male pilots engaged in a counterbalanced experimental protocol comparing a 0-m normoxic condition (NORM) with a 3810-m hypoxic condition (HYP) on pilot physiology, cognition and flight performance. RESULTS: Repeated-measures analysis of variance demonstrated a significant (p ≤ 0.05) time by condition interaction for physiological and cognitive alterations during HYP. A paired-samples t test demonstrated no differences in pilot performance (p ≥ 0.05) between conditions. CONCLUSION: Pilots exhibited physiological and cognitive impairments; however, pilot performance was not affected by HYP.

The cardiovascular response to passive movement is joint dependent.

The cardiovascular responses to passive limb movement (PLM) at the knee are well established, however, responses to PLM at other joints involving smaller muscle volume are unknown. To compare the cardiovascular responses to passive movement at other joints, 10 participants underwent a PLM protocol in which the wrist, elbow, ankle, and knee joints were passively extended and flexed at 1 Hz for 1 min. Heart rate (HR), mean arterial blood pressure (MAP), and arterial blood flow to that limb segment (BF) were measured and vascular conductance (VC) was calculated for a 30-sec baseline period and for 3-sec intervals throughout PLM protocols. PLM of the knee and elbow resulted in significant increases in BF and VC from baseline values with peak values 180% (P < 0.001) greater than baseline. PLM of the elbow resulted in significant increases in BF and VC from baseline values with peak values 109% and 115% (P < 0.001) greater than baseline, respectively. No changes in BF and VC were observed in the ankle and wrist. Furthermore, the greater increase in blood flow per limb segment volume in the thigh and upper arm (62.8 ± 36.5 and 55.5 ± 30.3 mL min(-1) L(-1), respectively) compared to the forearm and lower leg (23.6 ± 16.7 and 19.1 ± 10.3 mL min(-1) L(-1), respectively) indicates the limb volume is not solely responsible for the differences in the hyperemic responses. These data indicate that the use of PLM to assess vascular function or as a rehabilitation modality to maintain vascular health may be most appropriate for the muscles that span the elbow and knee.

Exercise Improves Mood State in Normobaric Hypoxia.

BACKGROUND: The purpose of this study was to quantify the efficacy of using exercise to alleviate the impairments in mood state associated with hypoxic exposure. METHODS: Nineteen young, healthy men completed Automated Neuropsychological Assessment Metrics-4(th) Edition (ANAM4) versions of the mood state test before hypoxia exposure, after 60 min of hypoxia exposure (12.5% O(2)), and during and after two intensities of cycling exercise (40% and 60% adjusted Vo(2max)) under the same hypoxic conditions. Peripheral oxygen saturation (Spo(2)) and regional cerebral oxygen saturation (rSo(2)) were continuously monitored. RESULTS: At rest in hypoxia, Total Mood Disturbance (TMD) was significantly increased compared to baseline in both the 40% and 60% groups. TMD was significantly decreased during exercise compared to rest in hypoxia. TMD was also significantly decreased during recovery compared to rest in hypoxia. Spo(2) significantly decreased at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. Regional cerebral oxygen saturation was also reduced at 60 min rest in hypoxia, during exercise, and recovery compared to baseline. DISCUSSION: The current study demonstrated that exercise at 40% and 60% of adjusted Vo(2max) attenuated the adverse effects of hypoxia on mood. These findings may have significant applied value, as negative mood states are known to impair performance in hypoxia. Further studies are needed to replicate the current finding and to clarify the possible mechanisms associated with the potential benefits of exercise on mood state in normobaric hypoxia.

Do glucose containing beverages play a role in thermoregulation, thermal sensation, and mood state?

INTRODUCTION: Dehydration limits the appropriate delivery of oxygen and substrates to the working muscle. Further, the brain's ability to function may also be compromised whereby thermal sensation and mood state may be altered. PURPOSE: The purpose of the present investigation was to compare the thermoregulatory, perceptual, and negative mood state profile in glucose (GLU) vs. non-glucose beverage (NON-GLU) condition. METHODS: Ten healthy men volunteered and were counterbalanced either a GLU or NON-GLU containing beverage on separate mornings. In each condition, they were exposed to 37°C, 50% relative humidity (RH) for baseline, exercise, rehydration, and recovery periods. The exercise period elicited the desired level of dehydration (mean of 2.6 ± 0.3% body weight losses). Upon completion of the protracted exercise, participants were administered either a GLU or NON-GLU containing electrolyte based sports drink ad libitum for 30 min, followed by a recovery period of 15 min in 37°C, 50% RH. Rectal (Tre) and mean skin temperatures (Tsk) were continuously monitored. Gagge (TS) and heated thermal sensation (HTS), profile of mood state (POMS) were measure at the end of each period. RESULTS: During recovery after rehydration, Tre was not significantly different between conditions (GLU vs. NON-GLU) (37.4 ± 0.8 vs. 37.0 ± 1.2°C); Tsk was also not affected by rehydration in both conditions (36.0 ± 0.5 vs. 36.0 ± 0.6°C) and, TS and HTS did not differ between conditions (0.9 ± 1.3 vs.1.3 ± 0.7) and (1.0 ± 0.8 vs.0.8 ± 0.3). Total mood disturbance (TMD) score for the POMS was utilized for overall negative mood state and demonstrated a main effect for time (p < 0.05). TMD during recovery was decreased compared to before hydration in both conditions. CONCLUSION: The non-glucose containing beverage maintained plasma volume and was effective at maintaining body temperature homeostasis in a similar fashion compared to the glucose containing beverage. Furthermore, negative mood state was not different between the two conditions. The non-glucose beverages can serve a valuable role in the exercise environment depending upon the sport, the ambient temperature, the individual, duration of the exercise, the age and training states of the individual.

Cardiovascular responses to counterweighted single-leg cycling: implications for rehabilitation.

PURPOSE: Although difficult to coordinate, single-leg cycling allows for greater muscle-specific exercise capacity and subsequently greater stimulus for metabolic and vascular adaptations compared to typical double-leg cycling. The purpose of this investigation was to compare metabolic, cardiovascular and perceptual responses of double-leg cycling to single-leg cycling with and without the use of a counterweight. METHODS: Ten healthy individuals (age 22 ± 2 years; body mass 78.0 ± 11.2 kg; height 1.8 ± 0.1 m) performed three cycling conditions consisting of double-leg cycling (DL), non-counterweighted single-leg cycling (SLNCW) and single-leg cycling with a 97 N counterweight attached to the unoccupied crank arm (SLCW). For each condition, participants performed cycling trials (80 rpm) at three different work rates (40, 80 and 120 W). Oxygen consumption (VO2), respiratory exchange ratio (RER), heart rate (HR), femoral blood flow, rating of perceived exertion (RPE) and liking score were measured. RESULTS: VO2 and HR were similar for DL and SLCW conditions. However, during SLNCW, VO2 was at least 23 ± 13 % greater and HR was at least 15 ± 11 % greater compared to SLCW across all three intensities. Femoral blood flow was at least 65.5 ± 43.8 % greater during SLCW compared to DL cycling across all three intensities. RPE was lower and liking scores were greater for SLCW compared to SLNCW condition. CONCLUSION: Counterweighted single-leg cycling provides an exercise modality that is more tolerable than typical single-leg cycling while inducing greater peripheral stress for the same cardiovascular demand as double-leg cycling.

Cold habituation does not improve manual dexterity during rest and exercise in 5 °C.

When exposed to a cold environment, a barehanded person experiences pain, cold sensation, and reduced manual dexterity. Both acute (e.g. exercise) and chronic (e.g. cold acclimatization or habituation) processes might lessen these negative effects. The purpose of this experiment was to determine the effect of cold habituation on physiology, perception, and manual dexterity during rest, exercise, and recovery in 5 °C. Six cold weather athletes (CWA) and eight non habituated men (NON) volunteered to participate in a repeated measures cross-over design. The protocol was conducted in 5 °C and was 90 min of resting cold exposure, 30 min of cycle ergometry exercise (50 % VO2 peak), and 60 min of seated recovery. Core and finger skin temperature, metabolic rate, Purdue Pegboard dexterity performance, hand pain, thermal sensation, and mood were quantified. Exercise-induced finger rewarming (EIFRW) was calculated for each hand. During 90 min of resting exposure to 5 °C, the CWA had a smaller reduction in finger temperature, a lower metabolic rate, less hand pain, and less negative mood. Despite this cold habituation, dexterity performance was not different between groups. In response to cycle ergometry, EIFRW was greater in CWA (~12 versus 7 °C) and occurred at lower core temperatures (37.02 versus 37.31 °C) relative to NON but dexterity was not greater during post-exercise recovery. The current data indicate that cold habituated men (i.e., CWA) do not perform better on the Purdue Pegboard during acute cold exposure. Furthermore, despite augmented EIFRW in CWA, dexterity during post-exercise recovery was similar between groups.

Validity of Borg Ratings of Perceived Exertion During Active Video Game Play.

During physically interactive video game play (e.g., Nintendo Wii), users are exposed to potential distracters (e.g., video, music), which may decrease their ratings of perceived exertion (RPE) throughout game play. The purpose of this investigation was to determine the association between RPE scores and heart rate while playing the Nintendo Wii. Healthy adults (N = 13, 53.5 ± 5.4 years old) participated in two exercise sessions using the Nintendo Wii Fit Plus. During each session participants played a five-minute warm-up game (Basic Run), two separate Wii Fit Plus games (Yoga, Strength Training, Aerobics or Balance Training) for fifteen minutes each, and then a five-minute cool down game (Basic Run). Borg RPE and heart rate were assessed during the final 30 seconds of the warm up and cool down, as well during the final 30 seconds of play for each Wii Fit Plus game. Correlation analysis combining data from both exercise sessions indicated a moderate positive relationship between heart rate and RPE (r = 0.32). Mixed-effects model regression analyses demonstrated that RPE scores were significantly associated with heart rate (p < 0.001). The average percentage of age-predicted heart rate maximum achieved (58 ± 6%) was significantly greater (p = 0.001) than the percentage of maximum RPE indicated (43 ± 11%). Borg RPE scores were positively associated with heart rate in adults during exercise sessions using the Wii Fit Plus. However, this relationship was lower than observed in past research assessing RPE validity during different modes of exercise (e.g. walking, running) without distracters.