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The primary purpose of the current investigation was to perform an intensity distribution analysis of a collegiate cross-country (CC) competition, with a secondary purpose to compare race times (RT) with modeled performance times (MPT). Participants completed an incremental treadmill test to determine gas exchange threshold (GET), while the three-minute all-out test was conducted on a 400 m outdoor track to determine critical velocity (CV) and D prime (D′). GET and CV were used as physiological markers for the intensity zones based on heart rate (HR) and running velocity (RV), while CV and D′ were used to determine modeled performance times. Participants wore a Global Positioning System (GPS) watch and heart rate (HR) monitor during competition races. Statistically, less time was spent in HR Zone 1 (12.1% ± 13.7%) compared to Zones 2 (37.6% ± 30.2%) and 3 (50.3% ± 33.7%), while a statically greater amount of time was spent in RV Zone 2 (75.0% ± 20.7%) compared to Zones 1 (8.4% ± 14.0%) and 3 (16.7% ± 19.1%). RTs (1499.5 ± 248.5 seconds (s)) were statistically slower compared to MPTs (1359.6 ± 192.7 s). The observed differences in time spent in each zone are speculated to be related to the influence of environmental conditions on internal metrics and difference in the kinetics of HR and running velocity. Differences in RTs and MPTs are likely due to the MPT equation modeling all-out performance and not considering race strategies. [ABSTRACT FROM AUTHOR]

The current investigation compared the acute oxygen consumption (VO2) response of two high-intensity interval exercises (HIIE), fast start (FSHIIE), and steady power (SPHIIE), which matched w prime (W') depletion. Eight cyclists completed an incremental max test and a three-minute all-out test (3MT) to determine maximal oxygen consumption (VO2max), critical power (CP), and W'. HIIE sessions consisted of 3 X 4 min intervals interspersed by 3 min of active recovery, with W' depleted by 60% (W'target) within each working interval. SPHIIE depleted the W'target consistently throughout the 3 min intervals, while FSHIIE depleted the W'target by 50% within the first minute, with the remaining 50% depleted evenly across the remainder of the interval. The paired samples t-test revealed no differences in the percentage of training time spent above 90% of VO2max (PT ≥ 90% VO2max) between SPHIIE and FSHIIE with an average of 25.20% and 26.07%, respectively. Pairwise comparisons indicated a difference between minute 1 peak VO2, minute 2, and minute 3, while no differences were present between minutes 2 and 3. The results suggest that when HIIE formats are matched based on W' expenditure, there are no differences in PT ≥ 90% VO2max or peak VO2 during each interval. [ABSTRACT FROM AUTHOR]

The purpose of the current investigation was to examine the effects of exercise intensity on asymmetry in pedal forces when the accumulation of fatigue is controlled for, and to assess the reliability of asymmetry outcomes during cycling. Participants completed an incremental cycling test to determine maximal oxygen consumption and the power that elicited maximal oxygen consumption (pVO2max). Participants were allotted 30 min of recovery before then cycling at 60%, 70%, 80%, and 90% of pVO2max for 3 min each, with 5 min of active recovery between each intensity. Participants returned to the laboratory on separate days to repeat all measures. A two-way repeated measures analysis of variance (ANOVA) was utilized to detect differences in power production AI at each of the submaximal exercise intensities and between Trials 1 and 2. Intraclass correlations were utilized to assess the test–retest reliability for the power production asymmetry index (AI). An ANOVA revealed no significant intensity–visit interactions for the power production AI (f = 0.835, p = 0.485, η2 = 0.077), with no significant main effects present. ICC indicated excellent reliability in the power production AI at all intensities. Exercise intensity did not appear to affect asymmetry in pedal forces, while excellent reliability was observed in asymmetry outcomes. [ABSTRACT FROM AUTHOR]

Persons with multiple sclerosis (PwMS) experience a variety of physical impairments that can present in an asymmetrical pattern, resulting in significant differences between contralateral limbs (i.e., >10%). Asymmetries in PwMS have been associated with walking impairment and postural instability. Exercise intensity has been shown to influence the degree of asymmetry outcomes in healthy populations, and may have an impact on appropriate exercise prescriptions. The purpose of the current pilot study was to investigate the potential presence of asymmetry in metabolic events demarcating exercise intensity domains during single-leg cycling in PwMS. Five PwMS (Expanded Disability Status Scale range 2.0 to 4.5) completed a single leg incremental cycling test (SLICT) and a series of single-leg constant power time-to-exhaustion trials to determine gas exchange threshold (GET), peak oxygen consumption (VO2peak), peak power output (PPO), critical power (CP), and W' (exercise tolerance above CP) for both lower limbs. Statistical analysis revealed no significant between-limb differences for VO2peak, GET, CP, PPO, and W'. Only W' asymmetry score was significantly (49.5 ± 28.7 vs. 10.0, p = 0.04) greater than 10%. No significant differences between asymmetry scores at the GET, CP, and PPO were observed. Results from the current pilot investigation suggest that exercise intensity may not influence asymmetry outcomes in PwMS. Future studies with larger sample sizes and those with higher disability levels are required to fully understand the influence of exercise intensity on asymmetry in PwMS. [ABSTRACT FROM AUTHOR]

The power/velocity-duration curve consists of critical power (CP), the highest work rate at which a metabolic steady state can obtained, and W' (e.g., W prime), the finite amount of work that can be performed above CP. Significant associations between CP and performance during endurance sports have been reported resulting in CP becoming a primary outcome for enhancement following exercise training interventions. This review evaluated and summarized the effects of different exercise training methodologies for enhancing CP and respective analogs. A systematic review was conducted with the assistance of a university librarian and in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Ten studies met the criteria for inclusion and were reviewed. Four, 2, 2, 1, and 1 articles included swimming, cycling, resistance training, rowing, and running, respectively. Improvements in CP, and respective analogs, were reported in 3 swimming, 2 cycling, and 1 rowing intervention. In addition, only 2 cycling and 1 swimming intervention used CP, and respective analogs, as an index of intensity for prescribing exercise training, with one cycling and one swimming intervention reporting significant improvements in CP. Multiple exercise training modalities can be used to enhance the power/velocity-duration curve. Significant improvements in CP were often reported with no observed improvements in W' or with slight decreases. Training may need to be periodized in a manner that targets enhancements in either CP or W' but not simultaneously. [ABSTRACT FROM AUTHOR]

Background: Immune-mediated demyelination and consequent degeneration of oligodendrocytes and axons are hallmark features of multiple sclerosis (MS). Remyelination declines in progressive MS, causing permanent axonal loss and irreversible disabilities. Strategies aimed at enhancing remyelination are critical to attenuate disease progression. Objective: We systematically reviewed recent advances in neuroprotective and regenerative therapies for MS, covering preclinical and clinical studies. Methods: We searched three biomedical databases using defined keywords. Two authors independently reviewed articles for inclusion based on pre-specified criteria. The data were extracted from each study and assessed for risk of bias. Results: Our search identified 7351 studies from 2014 to 2020, of which 221 met the defined criteria. These studies reported 262 interventions, wherein 92% were evaluated in animal models. These interventions comprised protein, RNA, lipid and cellular biologics, small molecules, inorganic compounds, and dietary and physiological interventions. Small molecules were the most highly represented strategy, followed by antibody therapies and stem cell transplantation. Conclusion: While significant strides have been made to develop regenerative treatments for MS, the current evidence illustrates a skewed representation of the types of strategies that advance to clinical trials. Further examination is thus required to address current barriers to implementing experimental treatments in clinical settings. [ABSTRACT FROM AUTHOR]

Background: Lower limb strength asymmetry (ie, significant difference between contralateral limbs) has been associated with mobility impairment in persons with multiple sclerosis (MS). However, whether an adaptive exercise modality can be used to modify lower limb strength and potentially improve mobility is unclear. The effect of functional electrical stimulation (FES) cycling on lower limb strength asymmetry in persons with MS with mobility impairment was assessed, and the association between change in lower limb strength asymmetries and changes in functional and selfreported mobility outcomes was explored. Methods: Eight adults with MS (Expanded Disability Status Scale scores, 5.5-6.5) were included. Outcomes included knee extensor and knee flexor strength asymmetry, Timed 25-Foot Walk (T25FW) test, 2-Minute Walk Test (2MWT), Timed Up and Go (TUG) test, and 12-item Multiple Sclerosis Walking Scale (MSWS-12). Participants received 24 weeks (3 times per week) of FES cycling or passive leg cycling. Results: The FES condition demonstrated a small decrease in knee extensor (d = -0.33) and knee flexor (d = -0.23) strength asymmetry compared with passive leg cycling. With both groups combined, weak-to-strong associations were observed between change in knee extensor asymmetry and change in T25FW test time (rs = -0.43), 2MWT time (rs = -0.24), TUG test time (rs = 0.55), and MSWS-12 score (rs = 0.43). Moderate correlations were observed between change in knee flexor asymmetry and change in T25FW test time (rs = -0.31), TUG test time (rs = 0.33), and MSWS-12 score (rs = 0.35). Conclusions: FES cycling may be an efficacious exercise modality for reducing lower limb strength asymmetry and improving mobility in persons with MS. [ABSTRACT FROM AUTHOR]

Collegiate cross-country training is often conducted and prescribed in a group setting. This may result in the application of an inappropriate training stimulus to athletes due to potentially different physiological responses to the same training prescription. The aim of this investigation was to quantify the training intensity distribution (TID) of a collegiate cross-country team and the associated physiological adaptions. Sixteen subjects, 8 male subjects and 8 female subjects, performed a graded exercise test before and after observational period to determine peak oxygen consumption (V̇o2peak), the speed (S@), heart rate (HR@), and oxygen consumption (V̇o2@) associated with 2 and 4 mmol·L-1 of blood lactate. Training intensity distribution was quantified by assessing time spent in 3 intensity zones calculated as zone 1 (low intensity, HR values< HR@2); zone 2 (moderate intensity, HR values >HR@2 and HR@4). No statistical differences were observed between male subjects and female subjects for percent of training time spent in zones 1, 2, and 3. No significant interactions were observed between sex and time for performance variables. Male subjects and female subjects improved V̇o2peak, S@4, and V̇o2@4 with male subjects also increasing V̇o2@2. No significant differences were observed between male subjects and female subjects when comparing percent changes for variables. Examining individual data showed that 2 female subjects experienced performance decrements and trained proportionally more in zones 2 and 3 compared with the overall group. The TID and performance decrements of the 2 highlighted subjects suggest that conducting training in a group setting may potentially be detrimental for some collegiate runners. [ABSTRACT FROM AUTHOR]

Background: Persons with chronic neurological conditions (CNCs) often present with asymmetrical impairments, creating significant differences between contralateral limbs in body functions. These asymmetries have been associated with reduced mobility and balance, and are often targeted for reduction during rehabilitation. Exercise training has established benefits for persons with CNCs, and may have positive effects on asymmetry outcomes. Objectives: The purpose of this review was to summarize the current evidence for the effects exercise training on gait, balance, and physical fitness asymmetry in randomized control trials (RCTs) of persons with CNCs. Methods: A search of four electronic databases (EMBASE, CINAHL, SPORTdiscus, and ovidMEDLINE) was conducted following the structured Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: The search retrieved 3,493 articles, with 465 articles assessed for eligibly, and nine articles meeting the criteria for inclusion. Of the included articles, five incorporated resistance exercise, three incorporated aerobic exercise, and one incorporated combined exercise (i.e., resistance and aerobic exercise). Gait asymmetry improved significantly in four studies after resistance, aerobic, and combined exercise. Significant improvements in weight bearing asymmetry were reported in three studies after resistance exercise. One study reported significant improvements in both gait and balance asymmetry after resistance exercise. Conclusions: Preliminary evidence suggests that exercise training, as a component of rehabilitation, may have positive effects on gait and balance asymmetry in persons with CNCs. Several limitations of the current literature were noted, including a limited number of studies, combination of exercise with other rehabilitation modalities, a lack of reporting on exercise prescriptions (e.g., number of repetitions, intensity), and variability in the calculation of asymmetry outcomes. These limitations prevent definitive conclusions on the effects of exercise training on asymmetry outcomes. Future trials are needed to determine the potential of exercise training for reducing asymmetry in persons with CNCs. [ABSTRACT FROM AUTHOR]

Studies have shown that when aerobic exercise is supplemented with muscular endurance training metabolic adaptions occur that result in the delay of the onset of blood lactate accumulation (OBLA). However, previous studies have not explored any submaximal cardiorespiratory adaptations that may result from this training protocol. The aim of the current investigation was to evaluate the effect of supplementing an aerobic exercise training program with a muscular endurance training program on various cardiorespiratory and metabolic measurements. Fourteen aerobically active men performed an incremental exercise test to determine the OBLA, gas exchange threshold (GET), and maximal oxygen uptake (...O2max). Maximal strength was measured using 1 repetition maximum (1RM) for leg press (LP), leg curl (LC), and leg extension (LE). Eight subjects supplemented their aerobic activity (experimental [EX] group) with 8 weeks of muscular endurance training, while 6 continued their regular aerobic activity (control [CON] group). No significant group differences were observed for all pretraining variables. After 8 weeks of training, no significant differences in body mass, GET, and ...O2max were observed for either group. However, the EX group showed a significant improvement for both absolute and relative ...O2 at OBLA compared with the CON group. Leg curl and LE 1RM assessments for the EX group showed a significant improvement compared with CON group. Muscular endurance training did not improve GET and ...O2max, but significantly increased ...O2 at OBLA, LP, and LC. These find- ings suggest that this training protocol maybe useful in the development of submaximal aerobic performance and leg strength for endurance athletes. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if onset of blood lactate (OBLA) using the fixed at 4 mmol$L21 method could be delayed by supplementing high-volume resistance training (HVRT) to existing endurance training programs. There were 20 male subjects who participated in the study; 11 experimental (EX) (22.8±4.6 years) and 9 controls (CON) (23.2±5.8 years). An incremental cycling test was performed to determine maximal oxygen uptake, OBLA, maximum power, and time to exhaustion. Additionally, strength of the leg press (LP), leg curl (LC), and leg extension (LE) was assessed in both groups. Participants continued their ongoing endurance training, whereas the EX group supplemented their training with HVRT twice weekly for 8 weeks, performing 4 sets of 15 repetitions of LP, LC, and LE. Change score (post-pre) analysis was measured, using t-tests to compare the differences between groups, to eliminate outside variables that may have affected testing performance. Significance was set at p # 0.05. No significant group differences in baseline measures were observed. A significant difference was observed for OBLA at 4 mmol·L-1 (EX: 18.17±15.36 W and CON: 23.52±20.13 W, p, 0.02). A significant difference was observed for LP (EX: 39.09±25.87 kg and CON: 4.22±34.65 kg, p, 0.02) and LC (EX: 22.84±8.7 kg and CON: 21.47±8.2 kg, p, 0.01). Supplementing HVRT in endurance-trained individuals delayed OBLA at 4 mmol·L-1 and improved leg strength. The HVRT used in the current study may be a useful training style for endurance-trained individuals. [ABSTRACT FROM AUTHOR]

Background: Lower limb strength asymmetries (ie, difference ≥10% between contralateral muscle groups) have been associated with mobility impairment in persons with multiple sclerosis (PwMS), and may be a target for exercise training interventions aiming to improve mobility. Functional electrical stimulation (FES) cycling is an adapted exercise modality that has demonstrated preliminary benefits for mobility and fitness outcomes in PwMS with mobility impairment, but its potential effects on lower limb strength asymmetry remain unknown. Objectives: To assess the effect of FES cycling exercise on lower limb strength asymmetry in PwMS who have mobility impairment (ie, Expanded Disability Status Scale [EDSS] score 5.5-6.5), and to explore associations between change in lower limb strength asymmetry and change in mobility outcomes. Methods: Peak torque was recorded bilaterally for knee extensors (KEs) and flexors (KFs) using an isokinetic dynamometer, and was then used to generate lower limb strength asymmetry scores (1-(torqueweak/torquestrong) x 100). Mobility outcomes included the Timed 25-Foot Walk (T25FW) and the 2-Minute Walk (2MW). Participants received 24 weeks (3x/week) of either FES cycling or passive leg cycling (PLC). The FES condition actively cycled while receiving mild electrical stimulation to the quadriceps, hamstrings, and gluteal muscle groups. Exercise intensity was set at 40% to 60% of heart rate reserve, with exercise duration gradually increasing from 10 to 40 minutes per session over the course of the intervention. The PLC condition was identical to the FES condition, but did not receive electrical stimulation and did not actively cycle. Results: Eight PwMS (mean [SD] age = 52.9 [7.9]; median [IQR] EDSS score = 6.3 [0.5]) completed the intervention. The FES cycling condition demonstrated a small decrease in KE (d = -0.33) and KF (d = -0.23) asymmetry compared to the PLC condition. Small-to-moderate associations were observed between change in KE asymmetry and change in T25FW (ρ = -0.43) and 2MW (ρ = -0.24). A moderate association was observed between change in KF asymmetry and change in T25FW (ρ = -0.31), while no association was observed with change in 2MW (ρ = -0.07). Conclusions: FES cycling may be efficacious for reducing lower limb strength asymmetry and improving mobility in PwMS who have mobility impairment. These preliminary results will inform future FES cycling investigations with larger sample sizes. [ABSTRACT FROM AUTHOR]