High-Speed Cycling Intervention Improves Rate-Dependent Mobility in Older Adults

Upper-Limb Muscle Fatigability in Para-Athletes Quantified as the Rate of Force Development in Rapid Contractions of Submaximal Amplitude

This study aimed to compare neuromuscular fatigability of the elbow flexors and extensors between athletes with amputation (AMP) and athletes with spinal cord injury (SCI) for maximum voluntary force (MVF) and rate of force development (RFD). We recruited 20 para-athletes among those participating at two training camps (2022) for Italian Paralympic veterans. Ten athletes with SCI (two with tetraplegia and eight with paraplegia) were compared to 10 athletes with amputation (above the knee, N = 3; below the knee, N = 6; forearm, N = 1). We quantified MVF, RFD at 50, 100, and 150 ms, and maximal RFD (RFDpeak) of elbow flexors and extensors before and after an incremental arm cranking to voluntary fatigue. We also measured the RFD scaling factor (RFD-SF), which is the linear relationship between peak force and peak RFD quantified in a series of ballistic contractions of submaximal amplitude. SCI showed lower levels of MVF and RFD in both muscle groups (all p values ≤ 0.045). Despite this, the decrease in MVF (Cohen's d = 0.425, p < 0.001) and RFDpeak (d = 0.424, p = 0.003) after the incremental test did not show any difference between pathological conditions. Overall, RFD at 50 ms showed the greatest decrease (d = 0.741, p < 0.001), RFD at 100 ms showed a small decrease (d = 0.382, p = 0.020), and RFD at 150 ms did not decrease (p = 0.272). The RFD-SF decreased more in SCI than AMP (p < 0.0001). Muscle fatigability impacted not only maximal force expressions but also the quickness of ballistic contractions of submaximal amplitude, particularly in SCI. This may affect various sports and daily living activities of wheelchair users. Early RFD (i.e., ≤50 ms) was notably affected by muscle fatigability.

Changes in Lower-Extremity Gait Biomechanics Following High-Cadence Cycling

We sought to investigate the lower-extremity biomechanics underlying increased gait velocity following high-cadence cycling. Ground reaction forces (GRF) and lower-extremity kinematics and kinetics were recorded as 15 healthy adults walked at a self-selected pace prior to and immediately following a 15 min bout of cycling at a cadence of 75 rotations per minute. Propulsive GRF and stance-phase peak dorsiflexion and knee extension angles increased, while peak plantarflexion and hip extension angles decreased. Swing-phase peak dorsiflexion, plantarflexion, knee flexion, and hip flexion angles increased, while peak knee extension angle decreased. Peak dorsiflexion, knee extension, and hip extension angular velocity also increased during swing. No changes in peak joint moments were observed; however, peak positive ankle, knee, and hip joint power generation increased following cycling. Completing high-cadence cycling improves gait velocity by increasing propulsive GRF; increasing joint angular velocity during the swing phase of gait for the ankle, knee, and hip; and increasing positive power production by the ankle, knee, and hip during the stance phase. Increased gait velocity post cycling exercise did not increase lower-extremity joint moments. Cycling may be a viable exercise-based modality for increasing gait velocity, especially in populations where gait ability or joint loading is of particular concern.

Interactive boxing-cycling on frailty and activity limitations in frail and prefrail older adults: A randomized controlled trial

BACKGROUND

Frailty is common among older adults, often associated with activity limitations during physical and walking tasks. The interactive boxing-cycling combination has the potential to be an innovative and efficient training method, and our hypothesis was that interactive boxing-cycling would be superior to stationary cycling in improving frailty and activity limitations in frail and prefrail older adults.

OBJECTIVE

To examine the impact of interactive boxing-cycling on frailty and activity limitations in frail and prefrail older adults compared to stationary cycling.

MATERIALS AND METHODS

A single-blinded randomized controlled trial. Forty-five participants who met at least one frailty phenotype criteria were randomly assigned to receive either interactive boxing-cycling (n = 23) or stationary-cycling (n = 22) for 36 sessions over 12 weeks. The interactive boxing-cycling was performed on a cycle boxer bike with an interactive boxing panel fixed in front of the bike. The primary outcomes were frailty status, including score and phenotypes. Secondary outcomes included activity limitations during physical and walking tasks. The pre- and post-intervention data of both groups were analyzed using a repeated measures two-way ANOVA.

RESULTS

Both types of cycling significantly improved frailty scores (p<0.001). Interactive boxing-cycling was more effective than stationary cycling in reversing the frailty phenotype of muscle weakness (p = 0.03, odds ratio 9.19) and demonstrated greater improvements than stationary cycling in arm curl (p = 0.002, η2=0.20), functional reach (p = 0.001, η2=0.22), and grip strength (p = 0.02, η2=0.12) tests. Additionally, interactive boxing-cycling exhibited a greater effect on gait speed (p = 0.02, η2=0.13) and gait variability (p = 0.01, η2=0.14) during dual-task walking.

CONCLUSION

In frail and prefrail older adults, interactive boxing-cycling effectively improves frailty but is not superior to stationary cycling. However, it is more effective at improving certain activity limitations.

REGISTRATION NUMBER

TCTR20220328001.

High cadence cycling not high work rate, increases gait velocity post-exercise

Gait velocity, or walking speed, has been referred to as the sixth vital sign, and research suggests that it is highly sensitive to change. Previous research has demonstrated the utility of cycling to improve gait parameters and in particular gait velocity in a variety of populations. However, it is unclear if the benefits from cycling to gait velocity stem from increased cadence, increased work rate, or the interaction between them. Therefore, the objective of the current research was to explicitly test the relationship between cycling work rate, cycling cadence, and gait velocity. 45 recreationally active young adults were randomly assigned to cycle at a normalised cadence and work rate, a higher cadence, or a higher work rate (CONTROL, FAST, HARD). All participants completed two ten-metre walk tests (10 MWT) pre- and post-cycling intervention. There was a significant interaction between group and time and post hoc comparisons showed that the FAST group walked significantly faster than the HARD group post-cycling. These results support the hypothesis that cycling at a cadence greater than the comfortable walking cadence, and not cycling at an increased work rate, increased gait velocity post-exercise for all members of our sample of healthy young adults.

Decreased neural drive affects the early rate of force development after repeated burst-like isometric contractions

The neural drive to the muscle is the primary determinant of the rate of force development (RFD) in the first 50 ms of a rapid contraction. It is still unproven if repetitive rapid contractions specifically impair the net neural drive to the muscles. To isolate the fatiguing effect of contraction rapidity, 17 male adult volunteers performed 100 burst-like (i.e., brief force pulses) isometric contractions of the knee extensors. The response to electrically-evoked single and octet femoral nerve stimulation was measured with high-density surface electromyography (HD-sEMG) from the vastus lateralis and medialis muscles. Root mean square (RMS) of each channel of HD-sEMG was normalized to the corresponding M-wave peak-to-peak amplitude, while muscle fiber conduction velocity (MFCV) was normalized to M-wave conduction velocity to compensate for changes in sarcolemma properties. Voluntary RFD 0-50 ms decreased (d = -0.56, p < 0.001) while time to peak force (d = 0.90, p < 0.001) and time to RFDpeak increased (d = 0.56, p = 0.034). Relative RMS (d = -1.10, p = 0.006) and MFCV (d = -0.53, p = 0.007) also decreased in the first 50 ms of voluntary contractions. Evoked octet RFD 0-50 ms (d = 0.60, p = 0.020), M-wave amplitude (d = 0.77, p = 0.009) and conduction velocity (d = 1.75, p < 0.001) all increased. Neural efficacy, i.e., voluntary/octet force ratio, largely decreased (d = -1.50, p < 0.001). We isolated the fatiguing impact of contraction rapidity and found that the decrement in RFD, particularly when calculated in the first 50 ms of muscle contraction, can mainly be explained by a decrease in the net neural drive.

Is moderate resistance training adequate for older adults with sarcopenia? A systematic review and network meta-analysis of RCTs

BACKGROUND

Resistance training (RT) and nutritional supplementation are recommended for the management of sarcopenia in older adults. However, optimal RT intensity for the treatment of sarcopenia has not been well investigated.

METHODS

This network meta-analysis aims to determine the comparative effectiveness of interventions for sarcopenia, taking RT intensity into consideration. RT intensity was classified into light-to-moderate intensity RT(LMRT), moderate intensity RT(MRT), and moderate-to-vigorous intensity RT(MVRT) based on percentage of one repetition maximum (%1RM) and/or rating of perceived exertion.

RESULTS

A total of 50 RCTs (N = 4,085) were included after screening 3,485 articles. The results confirmed that RT with or without nutrition was positively associated with improved measures of muscle strength and physical performance. Regarding RT intensity, LMRT only demonstrated positive effects on hand grip (aerobic training + LMRT + nutrition: mean difference [MD] = 2.88; 95% credential intervals [CrI] = 0.43,5.32). MRT provided benefits on improvement in the 30-s chair stand test (repetitions) (MRT: MD = 2.98, 95% CrI = 0.35,5.59), timed up and go test (MRT: MD = -1.74, 95% CrI: = -3.34,-0.56), hand grip (MRT: MD = 2.44; 95% CrI = 0.03,5.70), and leg press (MRT: MD = 8.36; 95% CrI = 1.87,13.4). MVRT also improved chair stand test repetitions (MVRT: MD = 5.64, 95% CrI = 0.14,11.4), gait speed (MVRT + nutrition: MD = 0.21, 95% CrI = 0.003,0.48), appendicular skeletal muscle index (MVRT + nutrition: MD = 0.25, 95% CrI = 0.01,0.5), and leg press (MVRT: MD = 14.7, 95% CrI: 5.96,22.4; MVRT + nutrition: MD = 17.8, 95% CrI: 7.55,28.6).

CONCLUSION

MVRT had greater benefits on muscle mass, lower extremity strength, and physical performance compared to MRT. Increasing RT intensity may be recommended for sarcopenic older adults.

The rate of force relaxation scaling factor is highly sensitive to detect upper and lower extremity motor deficiencies in mildly affected people with multiple sclerosis

BACKGROUND

The motor symptoms affecting upper and lower extremity functioning in people with multiple sclerosis (PwMS) are considered the cardinal symptoms of multiple sclerosis. There is still a need for outcome measures that can sensitively evaluate these symptoms. We aimed to investigate the sensitivity of the isometric outcomes (maximum force; Fmax, maximum rate of force development; RFDmax, rate of force development scaling factor; RFD-SF, and rate of force relaxation scaling factor; RFR-SF) and standard clinical tests (9-hole peg test; 9HPT and timed 25-feet walk test; T25FW) in detecting the upper and lower extremity motor deficiencies in PwMS and also in a subgroup of mildly affected PwMS whose performance in standard clinical tests were similar to controls.

METHODS

Twenty-nine PwMS (age: 47.9 (8.6) years, relapsing-remitting type, expanded disability status scale: 2.5 (1.5)) and their age- and gender-matched controls completed an identical testing protocol in the upper (grip force muscles) and lower (knee extensors) extremities. For each extremity, we assessed Fmax, RFDmax, RFD-SF, and RFR-SF. Additionally, participants completed standard clinical tests for the evaluation of upper- (9HPT) and lower-extremity (T25FW) function. Comparisons were made between controls and PwMS 1) using all study participants and 2) including only mildly affected PwMS whose performance in standard functional tests was comparable to controls. Independent sample t-tests were utilized to compare groups, with a p-value set at 0.01 to correct for multiple comparisons. P-values and effect sizes were used to evaluate the sensitivity of the outcome measures in detecting group differences.

RESULTS

Our results indicate that most isometric outcomes and standard functional tests were sensitive in detecting motor deficiencies in both upper and lower extremities between groups (p<0.001). Among participants, 16 PwMS in 9HPT and 11 PwMS in T25FW demonstrated performance similar to that of the control group (9HPT: 18.85 (2.20) s vs 17.81 (2.19) s; p=0.19) and (T25FW: 3.60 (0.42) s vs 3.58 (0.29) s; p=0.92). The results of the comparisons between mildly affected PwMS and their controls indicate that RFR-SF is the only sensitive isometric outcome to detect differences between groups in the upper (-8.24 (0.76) 1/s vs -8.93 (0.6) 1/s; p=0.008) and lower extremity (-5.86 (1.13) 1/s vs -7.71 (1.11) 1/s; p<0.001).

CONCLUSION

The rate of force relaxation scaling factor, which assesses the ability to rapidly relax muscle forces after quick contractions, demonstrates high sensitivity in detecting motor deficiencies in PwMS, even when the current standard clinical outcomes fail to detect these differences. Our findings emphasize the importance of future randomized controlled trials focusing on rehabilitative and therapeutic interventions that specifically target muscle force relaxation to enhance motor functioning in PwMS.

Increased Comfortable Gait Speed Is Associated With Improved Gait Biomechanics in Persons With Chronic Stroke Completing an 8-Week Forced-Rate Aerobic Cycling Intervention: A Preliminary Study

ABSTRACT

Task-specific gait training is recommended to improve locomotor function after stroke. Our objective was to determine the effects of a forced-rate aerobic exercise intervention on gait velocity and biomechanics in the absence of task-specific gait training. Individuals with chronic stroke ( N = 14) underwent 24 sessions of forced-rate aerobic exercise, at a targeted aerobic intensity of 60%-80% of their heart rate reserve. Change in comfortable walking speed in addition to spatiotemporal, kinematic, and kinetic variables were measured using three-dimensional motion capture. Overground walking capacity was measured by the 6-min walk test. To determine gait biomechanics associated with increased walking speed, spatiotemporal, kinematic, and kinetic variables were analyzed separately for those who met the minimal clinically important difference for change in gait velocity compared with those who did not. Participants demonstrated a significant increase in gait velocity from 0.61 to 0.70 m/sec ( P = 0.004) and 6-min walk test distance from 272.1 to 325.1 meters ( P < 0.001). Those who met the minimal clinically important difference for change in gait velocity demonstrated significantly greater improvements in spatiotemporal parameters ( P = 0.041), ground reaction forces ( P = 0.047), and power generation ( P = 0.007) compared with those who did not. Improvements in gait velocity were accompanied by normalization of gait biomechanics.

Safer cycling in older age (SiFAr): effects of a multi-component cycle training. a randomized controlled trial

BACKGROUND

The risk of older adults being injured or killed in a bicycle accident increases significantly due to the age-related decline of physical function. Therefore, targeted interventions for older adults to improve safe cycling competence (CC) are urgently needed.

METHODS

The "Safer Cycling in Older Age" (SiFAr) randomized controlled trial investigated if a progressive multi-component training program related to cycling improves CC of older adults. Between June 2020 and May 2022, 127 community-dwelling persons living in the area Nürnberg-Fürth-Erlangen, Germany aged 65 years and older were recruited, who are either (1) beginners with the e-bike or (2) feeling self-reported unsteadiness when cycling or (3) uptaking cycling after a longer break. Participants were either randomized 1:1 to an intervention group (IG; cycling exercise program, 8 sessions within 3 months) or an active control group (aCG; health recommendations). The CC as primary outcome was tested not blinded in a standardized cycle course prior and after the intervention period and after 6-9 months, which consists of variant tasks requiring skills related to daily traffic situations. Regression analyses with difference of errors in the cycling course as dependent variable and group as independent variable adjusted for covariates (gender, number of errors at baseline, bicycle type, age and cycled distance) were performed.

RESULTS

96 participants (73.4 ± 5.1 years; 59.4% female) were analyzed for primary outcome. Compared to the aCG (n = 49), the IG (n = 47) made an average of 2.37 fewer errors in the cycle course after the 3 months intervention period (p = 0.004). People with more errors at baseline had higher potential for improvement (B=-0.38; p < 0.001). Women on average made 2.31 (p = 0.016) more errors than men, even after intervention. All other confounders had no significant effect on the difference in errors. The intervention effect was very stable until 6-9 months after the intervention (B=-3.07, p = 0.003), but decreased with a higher age at baseline in the adjusted model (B = 0.21, p = 0.0499).

CONCLUSION

The SiFAr program increases cycling skills among older adults with self-perceived needs for improvement in CC and could easily be made available to a broad public due to its standardized structure and a train-the-trainer approach.

TRIAL REGISTRATION

This study was registered with clinicaltrials.gov: NCT04362514 (27/04/2020), https://clinicaltrials.gov/ct2/show/NCT04362514 .

Effect of High-Intensity Interval Training on Functional Movement in Older Adults: A Systematic Review and Meta-analysis

BACKGROUND

Preserving physiological functional capacity (PFC), the ability to perform the activities of daily life, and the ease with which they can be performed, in older adults, defined for this study as ≥ 50 years of age, is an important consideration for maintaining health and independence through the ageing process. Physical activity, and exercise training in particular, has been positively associated with improvement in PFC. In addition to improving aerobic and anaerobic capacity, promoting and preserving functional movement as a component of PFC is an important goal of physical activity, especially for older adults. High-intensity interval training (HIIT), an exercise protocol where repeated bouts of increased intensity are interspersed with active or passive recovery periods, has often been studied as an alternative to traditional moderate-intensity continuous training (MICT) exercise, where a continuous intensity is maintained throughout the exercise session. A large body of research has determined that both types of exercise programme are effective in improving measures of aerobic and anaerobic fitness in older adults. However, the effect of the two exercise modalities on functional movement has most often been a secondary outcome, with a range of observational techniques applied for measurement.

OBJECTIVES

The primary objective of this research is to systematically review and meta-analyse published studies of HIIT interventions that measured functional movement in older adults to conclude if HIIT is effective for improving functional movement. A secondary objective is to determine if there are significant differences between HIIT and MICT effect on functional movement.

METHODS

A search strategy of terms locating studies of HIIT interventions, functional movement outcome measures, and older adult population samples was executed on seven digital databases. Randomized and pair-matched trials of > 2 weeks were considered for inclusion. Studies of participants with neurological impairment or studies using combined exercise modality were rejected. Standardized mean difference for functional movement outcome measures was calculated. A meta-analysis of the included studies and subgroups was performed along with study quality (risk of bias and publication bias) evaluation.

RESULTS

A total of 18 studies were included in random effects model pooled analysis. Subgroup analysis of HIIT versus MICT on functional movement showed a trivial effect in favour of HIIT (ES 0.13, 95% CI [-0.06, 0.33] p = 0.18) and did not achieve statistical significance. However, HIIT showed a medium, statistically significant favourable effect on functional movement versus non-intervention control (ES = 0.60 95% CI [0.24, 0.95] p = 0.001). Further subgroups analysis using singular and multiple functional movement outcome measures showed similar results.

CONCLUSION

This meta-analysis indicates that HIIT interventions in older adults may be effective at promoting improvements in functional movement, though it is unclear whether HIIT is superior to MICT.

Measures of motor segmentation from rapid isometric force pulses are reliable and differentiate Parkinson's disease from age-related slowing

Some people with Parkinson's disease (PD) have disruptions in motor output during rapid isometric muscle contractions. Measures of such disruptions (motor segmentation) may help clarify disease subtype, progression, or effects of therapeutic interventions. We investigated the potential utility of segmentation measures by testing two hypotheses that are fundamental to measurement and evaluation. First, measures of motor segmentation are reliable from day to day (intraclass correlation coefficient > 0.8). Second, that measures of motor segmentation have the sensitivity to differentiate between people with PD and older adults. 10 subjects with PD had a mean age of 70.1 years, Hoehn-Yahr stage < 3, and median levodopa equivalent daily dose of 350 mg. Older adult (mean age 81.9 years) reference data are from a previously published study. Each subject provided approximately 87 rapid isometric index finger abduction force pulses up to 65% of their maximal isometric force for calculation of force pulse measures. Measures were computed for the excitation, transition, and relaxation phases of each force pulse. Measures of motor segmentation had high reliability and presented large (Cohen's D > 0.8) and significant (p < 0.05) group differences. In bivariate plots of selected measures, motor segmentation marked a departure of PD from age-related slowing. Across all subjects, greater segmentation was associated with greater impairments in rate control and a longer time to reach peak force (all Spearman's ρ > 0.8). These results support the potential utility of the motor segmentation measures by satisfying requirements for reliability and the sensitivity to indicate deviations from age-related slowing in motor output.

Relationship between hip abductor strength, rate of torque development scaling factor and medio-lateral stability in older adults

BACKGROUND

Recently, the rate of torque development scaling factor (RTD-SF) has been proposed as a useful tool that could contribute to a more comprehensive insight into muscular capacity. While lower RTD-SF is associated with ageing and certain neuromuscular diseases, it remains unknown whether this novel measure is associated with the postural control in the older adults.

RESEARCH QUESTION

Are hip abductor muscle strength, RTD and RTD-SF associated with responses to external postural perturbations in medio-lateral direction in older adults?

METHODS

Twenty healthy older adults (14 females, 6 males) were assessed for hip abductor muscle strength, RTD and RTD-SF, using a custom-built dynamometer. Perturbations were applied at waist level (4 perturbation intensities, 15 repetitions each) using a wire-pull paradigm, with centre-of-pressure (CoP) being recorded with force plates. For each condition (i.e. perturbation intensity), medio-lateral displacement and velocity of the CoP were computed. For both parameters, within-individual variation (representing consistency of the responses), expressed by the standard deviation (SD) of CoP parameters was also considered. Pearson correlation coefficients were computed between parameters of hip muscle capacity and CoP responses and SD values of CoP responses.

RESULTS

RTD-SF was moderately positively related to the consistency of the responses of both CoP displacement and velocity (r = 0.53-0.56; p = 0.011-0.016) at the lowest level of the perturbation magnitude (15 N). No other statistically significant relationships were found (all r < 0.35).

SIGNIFICANCE

RTD-SF could play a role in preserving postural balance in older adults when low-intensity perturbations are applied. RTD-SF is a novel outcome measure that could represent an important alternative clinical tool to traditional strength assessments. It could represent a supplementary tool to assess the risk of falls, however, several limitations and ambiguities need to be resolved by future research before it can be utilized in practice.

Survey of physical activity in persons with limb loss during the COVID-19 pandemic in the United States

BACKGROUND

Physical activity has been shown to be fundamental in the prevention of numerous diseases and disorders. Achieving and maintaining physical activity levels can be particularly challenging in those with impairments, such as those experiencing a lower limb amputation. To slow the spread of the virus, COVID-19 lockdown mandates imposed by the US state governments may have inadvertent consequences on physical activity levels of those dependent on specific forms of exercise. Understanding how physical activity levels may have affected persons with limb loss can inform intervention strategies for this vulnerable population.

OBJECTIVES

Examine the effects of the COVID-19 pandemic on physical activity levels in persons with limb loss.

STUDY DESIGN

Mixed-method design.

METHODS

A 20-item logic web-based survey and semistructured interviews were administered to individuals who were 18 years or older, spoke English, and had a history of lower limb loss. Quantitative data were analyzed using SPSS v25, whereas qualitative data were analyzed using constant comparison to formulate themes.

RESULTS

There were a significant effect on the amount of physical activity minutes performed per day, a negative effect on the ability to exercise and participate in societal engagements, and a series of barriers to performing physical activity because of the pandemic.

CONCLUSION

Physical activity was reduced significantly in persons with limb loss during the COVID-19 pandemic. A combination of health concerns, fitness center closures, and social distancing mandates were the primary drivers behind the decrease in activity.

Spatial Integration of Non-Motorized Transport and Urban Public Transport Infrastructure: A Case of Johannesburg

Sustainability of transport infrastructure integration begins with involving an all-inclusive transportation chain instead of only focusing on one part of the journey. This is achieved by facilitating spatial integration between diverse transport modalities to allow for a multiplicity of travel opportunities. This paper unpacks the extent of the spatial integration of non-motorized transport and urban public transport infrastructure within the city of Johannesburg in South Africa. Cycling activity datasets derived from Strava Metro and the spatial data of urban public transport infrastructures were collected to demonstrate existing spatial patterns and infrastructure connectivity. Exploratory spatial data analysis and focal statistics analysis were central in the data processing. The findings reveal that cycling activities are separated from urban public transport infrastructure, and the city of Johannesburg’s transport system is characterized by spatially fragmented commuting and cycling operations, with limited to no sharing of infrastructure. Most public transport stations are not easily accessible for non-motorized transport and are characterized by inadequate cycling facilities. In conclusion, the identification of an urban public transportation catchment area becomes essential for developing cities such as Johannesburg. This can be used as tool for planning infrastructural upgrades and forecasting potential public transport ridership while also assessing the impacts of investments in transit planning. There is thus a need to integrate motorized urban public transport and cycling infrastructural developments toward promoting multi-mobility and infrastructure sharing.

Quantification of Inter-Limb Symmetries With Rate of Force Development and Relaxation Scaling Factor

The inter-limb (a)symmetries have been most often assessed with the tests that quantify the maximal muscle capacity. However, the rapid force production and relaxation during submaximal tasks is equally important for successful sports performance. This can be evaluated with an established rate of force development and relaxation scaling factor (RFD-SF/RFR-SF). The aims of our study were (1) to assess the intra-session reliability of shortened RFD-SF/RFR-SF protocol and its absolute and symmetry outcome measures, (2) to compare the main absolute RFD-SF/RFR-SF outcome measures (slopes of RFD-SF and RFR-SF: kRTD-SF and kRFR-SF, theoretical peak RFD/RFR: TPRFD and TPRFR) across gender and sports groups, and (3) to compare inter-limb symmetries across gender and sports groups for main outcome measures (kRFD-SF, kRFR-SF, TPRFD, and TPRFR). A cross-sectional study was conducted on a group of young health participants (basketball and tennis players, and students): 30 in the reliability study and 248 in the comparison study. Our results showed good to excellent relative and excellent absolute reliability for the selected absolute and symmetry outcome measures (kRFD-SF, kRFR-SF, TPRFD, and TPRFR). We found significantly higher absolute values for kRFD-SF and TPRFD in males compared to females for the preferred (kRFD-SF: 9.1 ± 0.9 vs. 8.6 ± 0.9/s) and the non-preferred leg (kRFD-SF: 9.1 ± 0.9 vs. 8.5 ± 0.8/s), while there was no effect of sport. Significantly lower symmetry values for kRFR-SF (88.4 ± 8.6 vs. 90.4 ± 8.0%) and TPRFR (90.9 ± 6.8 vs. 92.5 ± 6.0%) were found in males compared to females. Moreover, tennis players had significantly higher symmetry values for kRFR-SF (91.1 ± 7.7%) and TPRFR (93.1 ± 6.0%) compared to basketball players (kRFR-SF: 88.4 ± 8.7% and TPRFR: 90.9 ± 6.7%) and students (kRFR-SF: 87.6 ± 8.7% and TPRFR: 90.5 ± 6.7%). Our results suggest that the reduced RFD-SF/RFR-SF protocol is a valuable and useful tool for inter-limb (a)symmetry evaluation. Differences in symmetry values in kRFR-SF and TPRFR (relaxation phase) were found between different sports groups. These may be explained by different mechanisms underlying the muscle contraction and relaxation. We suggest that muscle contraction and relaxation should be assessed for in-depth inter-limb symmetry investigation.

Advancements in the Protocol for Rate of Force Development/Relaxation Scaling Factor Evaluation

Brief submaximal actions are important for wide range of functional movements. Until now, rate of force development and relaxation scaling factor (RFD-SF and RFR-SF) have been used for neuromuscular assessment using 100-120 isometric pulses which requires a high level of attention from the participant and may be influenced by physiological and/or psychological fatigue. All previous studies have been conducted on a smaller number of participants which calls into question the eligibility of some of the outcome measures reported to date. Our aims were: (1) to find the smallest number of rapid isometric force pulses at different force amplitudes is still valid and reliable for RFD-SF slope (k _{R F D -SF}) and RFR-SF slope (k _RFR-SF ) calculation, (2) to introduce a new outcome measure - theoretical peak of rate of force development/relaxation (TP _RFD and TP _RFR ) and (3) to investigate differences and associations between k _RFD-SF and k _RFR-SF . A cross-sectional study was conducted on a group of young healthy participants; 40 in the reliability study and 336 in the comparison/association study. We investigated the smallest number of rapid isometric pulses for knee extensors that still provides excellent reliability of the calculated k _RFD-SF and k _RFR-SF (ICC₂,₁ ≥ 0.95, CV < 5%). Our results showed excellent reliability of the reduced protocol when 36 pulses (nine for each of the four intensity ranges) were used for the calculations of k _RFD-SF and k _RFR-SF . We confirmed the negligibility of the y-intercepts and confirmed the reliability of the newly introduced TP _RFD and TP _RFR . Large negative associations were found between k _RFD-SF and k _RFR-SF (r = 0.502, p < 0.001), while comparison of the absolute values showed a significantly higher k _RFD-SF (8.86 ± 1.0/s) compared to k _RFR-SF (8.03 ± 1.3/s) (p < 0.001). The advantage of the reduced protocol (4 intensities × 9 pulses = 36 pulses) is the shorter assessment time and the reduction of possible influence of fatigue. In addition, the introduction of TP _RFD and TP _RFR as an outcome measure provides valuable information about the participant's maximal theoretical RFD/RFR capacity. This can be useful for the assessment of maximal capacity in people with various impairments or pain problems.

Effects of a 12-Week Cycling Intervention on Successful Aging Measures in Mid-Aged Adults

Purpose: To compare the effect of 12-weeks of cycling training and competition versus recreational cycling on successful aging across physical, psychological, cognitive, and social functioning domains in mid-aged adults. Methods: Recreational cyclists were randomly assigned to an intervention (n = 13, M age = 47.18 years) and comparison (n = 13, M age = 46.91 years) group. Analysis of Covariance was used on self-reported pre-post data to determine changes across time and differences between groups on outcomes. Results: The intervention group scored higher on the role limitation due to physical problems measure of physical functioning (p = .045) and the social activity measure of social functioning (p = .008) with large effect sizes (η_p ² > .14). The remaining physical, psychological, cognitive, and social functioning measures were not significantly different (p > .05) between groups with small to medium effect sizes (η_p ² > .01 to ≤ .06). Conclusion: Cycling training and competition promotes better physical and social functioning than recreational cycling. This finding indicates that an intervention that incorporates the training and competition aspects of sport may promote positive outcomes that are above and beyond those that can be gained from participation in recreational physical activity. Objective measurements on larger samples across a broader range of sports are required to confirm and extend these findings.

Effect of Aerobic Exercise on Cardiopulmonary Responses and Predictors of Change in Individuals With Parkinson's Disease

OBJECTIVE

To determine the effect of aerobic exercise on maximal and submaximal cardiopulmonary responses and predictors of change in individuals with Parkinson's disease (PD).

DESIGN

Single-center, parallel-group, rater-blind study.

SETTING

Research laboratory.

PARTICIPANTS

Individuals with mild to moderate PD (N=100).

INTERVENTION

Participants were enrolled in a trial evaluating the effect of cycling on PD and randomized to either voluntary exercise (VE), forced exercise (FE), or a no exercise control group. The exercise groups were time and intensity matched and exercised 3×/wk for 8 weeks on a stationary cycle.

MAIN OUTCOME MEASURES

Cardiopulmonary responses were collected via gas analysis during a maximal graded exercise test at baseline and post intervention.

RESULTS

Exercise attendance was 97% and 93% for the FE and VE group, respectively. Average exercise heart rate reserve was 67%±11% for FE and 70%±10% for VE. No significant difference was present for change in peak oxygen consumption (VO₂peak) post intervention, even though the FE group had a 5% increase in VO₂peak. Both the FE and VE groups had significantly higher percentage oxygen consumption per unit time (V˙o₂) at ventilator threshold (VT) than the control group compared with baseline values (P=.04). Mean V˙O₂ at VT was 5% (95% CI, 0.1%-11%) higher in the FE group (P=.04) and 7% (2%, 12%) higher in VE group compared with controls. A stepwise linear regression model revealed that lower age, higher exercise cadence, and lower baseline VO₂peak were most predictive of improved VO₂peak. The overall model was found to be significant (P<.01).

CONCLUSIONS

Peak and submaximal cardiopulmonary function may improve after aerobic exercise in individuals with PD. Lower age, higher exercise cadence, and lower baseline VO₂peak were most predictive of improved VO₂peak in this exercise cohort. The improvements observed in aerobic capacity were gained after a relatively short aerobic cycling intervention.

Effect of a HIIT protocol on the lower limb muscle power, ankle dorsiflexion and dynamic balance in a sedentary type 1 diabetes mellitus population: a pilot study

Background

Type 1 diabetes mellitus (T1DM) is commonly associated with premature loss of muscle function, ankle dorsiflexion and dynamic balance. Those impairments, usually, lead to physical functionality deterioration. High-intensity interval training is an efficient and safety methodology since it prevents hypoglycemia and not requires much time, which are the main barriers for this population to practice exercise and increase physical conditioning. We hypothesized that a 6-week HIIT program performed on a cycle ergometer would increase lower limb muscle power, ankle dorsiflexion range of motion and dynamic balance without hypoglycemic situations.

Methods

A total of 19 diagnosed T1DM subjects were randomly assigned to HIIT group (n = 11; 6-week HIIT protocol) or Control group (n = 8; no treatment). Lower limb strength was evaluated through velocity execution in squat with three different overloads. Weight bearing lunge test (WBLT) was performed to test ankle dorsiflexion range of motion and Y-Balance test (YBT) was the test conducted to analyze dynamic balance performance.

Results

Velocity in squat improved a 11.3%, 9.4% and 10.1% (p < 0.05) with the 50%, 60% and 70% of their own body mass overload respectively, WBLT performance increased a 10.43% in the right limb and 15.45% in the left limb. YBT showed improvements in all directions (right limb-left limb): Anterior (4.3–6.1%), Posteromedial (1.8–5.2%) and Posterolateral (3.4–4.5%) in HIIT group (p < 0.05), unlike control group that did not experience any significant change in any of the variables (p > 0.05).

Conclusion

A 6-week HIIT program is safe and effective to improve execution velocity in squat movement, a fundamental skill in daily living activities, as well as ankle dorsiflexion range of motion and dynamic balance to reduce foot ulcers, risk falls and functional impairments. HIIT seems an efficient and safety training methodology not only for overcome T1DM barriers for exercising but also for improving functional capacities in T1DM people.

Dual and triple tasks performance in institutionalized prefrail and frail older adults

OBJECTIVE

The aim of this pilot study was to investigate differences on dual- and triple-task performance in institutionalized prefrail and frail older adults. Performance on these tasks is relevant since many activities of daily living involve simultaneous motor and cognitive tasks.

METHODS

We used a phenotypic description of frailty based on the presence or absence of five criteria related to physical fitness and metabolism (unintentional weight loss, self-reported exhaustion, muscle weakness, low gait speed, and low physical activity). Thirty-three institutionalized older adults (≥ 65 years, 78.8% females) were divided according to their frailty status. Participants completed cognitive tasks (a phonemic verbal fluency task and a visuospatial tracking task) while cycling on a stationary cycle (upper- and lower-extremity function was assessed). Cycling (number of arm and foot cycles) and cognitive (number of correct answers) performances were measured during single-, dual-, and triple-task conditions. Performances and costs of dual -and triple- tasking on cycling and cognitive performances were compared between prefrail and frail groups.

RESULTS

Prefrail and frail older adults did not differ in their performance in dual-tasks; however, frail older adults showed a poorer performance in the triple-task.

CONCLUSIONS

Although future studies need to confirm our observations in larger samples, this pilot study suggests that developing new tools based on triple tasking could be useful for the comprehensive assessment of frailty.

Forced and Voluntary Aerobic Cycling Interventions Improve Walking Capacity in Individuals With Chronic Stroke

OBJECTIVES

To determine the efficacy of high-intensity cycling to improve walking capacity in individuals with chronic stroke, identify variables that predict improvement in walking capacity, and quantify the relationship between the 6-minute walk test (6MWT) and cardiopulmonary exercise (CPX) test variables.

DESIGN

Secondary analysis of data from 2 randomized controlled trials.

SETTING

Research laboratory.

PARTICIPANTS

Individuals with chronic stroke (N=43).

INTERVENTIONS

Participants were randomized to 1 of the following time-matched interventions, occurring 3 times per week for 8 weeks: (1) forced aerobic exercise and upper extremity repetitive task practice (FE+RTP [n=16]), (2) voluntary aerobic exercise and upper extremity repetitive task practice (VE+RTP [n=14]), or (3) a non-aerobic control group (n=13).

MAIN OUTCOME MEASURE

Change in walking capacity as measured by the 6MWT from baseline to the end of treatment (EOT).

RESULTS

Significant increases were observed in distance traveled during the 6MWT at the EOT compared with baseline in the FE+RTP (P<.001) and VE+RTP (P<.001) groups, but not in the control group (P=.21). Among aerobic exercise participants, a multivariate regression analysis revealed that cycling cadence, power output, and baseline 6MWT distance were significant predictors of change in walking capacity.

CONCLUSIONS

An 8-week aerobic cycling intervention prescribed at 60% to 80% of heart rate reserve and moderate to high cadence and resistance led to significant improvements in walking capacity in our cohort of individuals with chronic stroke. Individuals with low baseline walking capacity levels may benefit most from aerobic cycling to improve over ground locomotion. Although the 6MWT did not elicit a cardiorespiratory response comparable to the maximal exertion CPX test, the 6MWT can be considered a valid and clinically relevant submaximal test of cardiorespiratory function in individuals with chronic stroke.

Age- and Sex-Related Differences in the Maximum Muscle Performance and Rate of Force Development Scaling Factor of Precision Grip Muscles

The aim of this study was to explore the effects of age and sex on the rate of force development scaling factor (RFD-SF) and maximum performance (i.e., maximum grip force [GFMax] and maximum rate of grip force development [RGFDMax]) of precision handgrip muscles. Sixty-four subjects, allocated in four groups according to their age and sex, were asked to hold an instrumented handle with the tip of the digits and perform two tests: maximum voluntary contraction and RFD-SF tests. In the maximum voluntary contraction test, GFMax and RGFDMax were assessed. In the RFD-SF test, the subjects generated quick isometric force pulses to target amplitudes varying between 20% and 100% of their GFMax. The RFD-SF and R2 values were obtained from the linear relationship between the peak values of the force pulses and the corresponding peak values of the rate of force development. Younger adults and males produced higher GFMax and RGFDMax and presented higher R2 and RFD-SF than older adults and females, respectively. No correlations between GFMax and RFD-SF and between RGFDMax and RFD-SF were observed.

The Musculoskeletal Health Benefits of Tennis

BACKGROUND

The prevalence of musculoskeletal (MSK) conditions is increasing, and although current guidelines for physical activity attempt to combat this, many fail to achieve the recommended targets. The present study sought to investigate whether regular tennis participation is more effective at enhancing MSK function than meeting the current international physical activity guidelines.

HYPOTHESIS

Tennis players will display significantly enhanced MSK function when compared with age-matched healthy active nonplayers.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Ninety participants (age range, 18-65 years) took part in this study; there were 43 tennis players (18 men, 25 women) and 47 nonplayers (26 men, 21 women). MSK function was assessed by cluster analysis of 3 factors: (1) electromyographic fatigability of prime movers during handgrip, knee extension, and knee flexion; (2) isometric strength in the aforementioned movements; and (3) body composition measured by bioelectrical impedance analysis. Maximal oxygen uptake was also assessed to characterize cardiorespiratory fitness.

RESULTS

Tennis players displayed significantly greater upper body MSK function than nonplayers when cluster scores of body fat percentage, handgrip strength, and flexor carpi radialis fatigue were compared by analysis of covariance, using age as a covariate (tennis players, 0.33 ± 1.93 vs nonplayers, -0.26 ± 1.66; P < 0.05). Similarly, tennis players also demonstrated greater lower extremity function in a cluster of body fat percentage, knee extension strength, and rectus femoris fatigue (tennis players, 0.17 ± 1.76 vs nonplayers, -0.16 ± 1.70; P < 0.05).

CONCLUSION

The present study offers support for improved MSK functionality in tennis players when compared with age-matched healthy active nonplayers. This may be due to the hybrid high-intensity interval training nature of tennis.

CLINICAL RELEVANCE

The findings suggest tennis is an excellent activity mode to promote MSK health and should therefore be more frequently recommended as a viable alternative to existing physical activity guidelines.

Development and Feasibility of a Regulated, Supramaximal High-Intensity Training Program Adapted for Older Individuals

Background: High-intensity training (HIT) with extremely short intervals (designated here as supramaximal HIT) is a time-efficient training method for health and performance. However, a protocol for regulation and control of intensity is missing, impeding implementation in various groups, such as older individuals. Methods: This study presents the development and characteristics of a novel training protocol with regulated and controlled supramaximal intervals adapted for older people. Using both quantitative and qualitative analyses, we explored the feasibility of the program, performed in a group training setting, with physically active older individuals (aged 65-75, n = 7; five women). The developed supramaximal HIT program consisted of 10 × 6 s cycle sprint intervals with ∼1 min of active recovery with the following key characteristics: (1) an individual target power output was reached and maintained during all intervals and regulated and expressed as the percentage of the estimated maximum mean power output for the duration of the interval (i.e., 6 s); (2) pedaling cadence was standardized for all participants, while resistance was individualized; and (3) the protocol enabled controlled and systematic adjustments of training intensity following standardized escalation criteria. Aim: Our aim was to test the feasibility of a novel training regimen with regulated and controlled supramaximal HIT, adapted for older people. The feasibility criteria for the program were to support participants in reaching a supramaximal intensity (i.e., power output > 100% of estimated VO2 max), avoid inducing a negative affective response, and have participants perceive it as feasible and acceptable. Results: All feasibility criteria were met. The standardized escalation procedure provided safe escalation of training load up to a supramaximal intensity (around three times the power output at estimated VO2 max). The participants never reported negative affective responses, and they perceived the program as fun and feasible. Conclusion: This novel program offers a usable methodology for further studies on supramaximal HIT among older individuals with different levels of physical capacity. Future research should explore the effects of the program in various populations of older people and their experiences and long-term adherence compared with other forms of training.

Relevance of evaluating the rate of torque development in ballistic contractions of submaximal amplitude

OBJECTIVE

The neuromuscular quickness capacity can be assessed by calculating the rate of torque development (RTD) during ballistic contractions of maximal (RTD_maximal) or submaximal (RTD_submaximal) amplitudes. In a series of ballistic contractions of submaximal amplitudes, the RTD scaling factor (RTD-SF) represents the slope of the linear regression between achieved peak torques and the corresponding RTD. First we investigated whether the RTD-SF contributes to the prediction, together with maximal voluntary torques (MVT), of the RTD_maximal. Then, we evaluated the agreement between the z-scores of RTD_maximal and RTD_submaximal.

APPROACH

The MVT was obtained for the quadriceps and hamstrings muscles of 22 elite young soccer players. RTD-SF was quantified in a series of ballistic contractions of submaximal and maximal amplitudes. RTD_submaximal was estimated from the regression relationship between the peak torques and the corresponding RTD.

MAIN RESULTS

MVT, RTD-SF and y -intercept in total accounted for 76.9 and 61.2% of the variance in RTD_maximal in quadriceps and hamstrings, respectively. Specifically, RTD-SF accounted for 13.7% and 18.7% of the variance in RTD_maximal, respectively. Generally, the agreement between the z-scores of RTD_maximal and RTD_submaximal was poor both in quadriceps and hamstrings.

SIGNIFICANCE

These results suggest that RTD-SF may have a functional relevance in the relationship between MVT and RTD_maximal and influence the amount of torque that can be achieved in a quick muscle contraction. Moreover, evaluating the RTD_submaximal does not provide results that are interchangeable with RTD_maximal. Thus, evaluating the RTD across the whole range of torque could provide additional meaningful information about neuromuscular quickness.

Interlimb Asymmetries Identified Using the Rate of Torque Development in Ballistic Contraction Targeting Submaximal Torques

Evaluating the rate of torque development (RTD) in isometric ballistic contraction targeting submaximal torques is usually overlooked in the literature. In a series of isometric ballistic contractions targeting a range of submaximal torque values, there is a linear relationship between the peak torque and the peak RTD obtained in each contraction. RTD scaling factor (RTD-SF) represents the slope of this relationship. In this study, we investigated the prevalence of interlimb asymmetry in the RTD-SF and in the RTD calculated across submaximal torques. Furthermore, we compared these asymmetry indices with those calculated adopting more classical approaches, such as ballistic contraction targeting maximal torque and isokinetic concentric conditions. Quadriceps and hamstrings strength was evaluated in both limbs of elite under 17 and under 19 soccer players (20 males, 17 ± 1 years). Participants performed three concentric isokinetic contractions at 240°/s and a series of isometric ballistic contractions targeting from 20 to 100% of maximal isometric torque. The interlimb difference was calculated for each parameter and players presenting an interlimb difference >15% were identified. A total of 40% (for quadriceps) and 60% (for hamstring) of players showed an interlimb asymmetry in isometric RTD for at least 50% of submaximal torque range. The RTD-SF was able to identify more players with asymmetry than the classical isokinetic tests. However, isokinetic and isometric indices of asymmetry were in general poorly or not correlated with each other. Most players presented an interlimb asymmetry in RTD for a wide part of the torque range and the adopted protocol was able to highlight important interindividual differences. Furthermore, players showed a large prevalence of RTD-SF asymmetry in both quadriceps and hamstrings. It is still to be determined if these asymmetries are functionally relevant. Nevertheless, the adopted protocol provided meaningful information for identifying interlimb asymmetries that could not be gathered when adopting the classical method of ballistic contractions targeting only maximal torques.

Neuromuscular Fatigue Does Not Impair the Rate of Force Development in Ballistic Contractions of Submaximal Amplitudes

The effect of muscle fatigue on rate of force development (RFD) is usually assessed during tasks that require participants to reach as quickly as possible maximal or near-maximal force. However, endurance sports require athletes to quickly produce force of submaximal, rather than maximal, amplitudes. Thus, this study investigated the effect of muscle fatigue induced by long-distance running on the capacity to quickly produce submaximal levels of force. Twenty-one male amateur runners were evaluated before and shortly after a half-marathon race. Knee extensors force was recorded under maximal voluntary and electrically evoked contractions. Moreover, a series of ballistic contractions at different submaximal amplitudes (from 20 to 100% of maximal voluntary force) was obtained, by asking the participants to reach submaximal forces as fast as possible. The RFD was calculated for each contraction. After the race, maximal voluntary activation, resting doublet twitch, maximal force, and RFD during maximal contraction decreased (-12, -12, -21, and -19%, respectively, all P-values < 0.0001). Nevertheless, the RFD values measured during ballistic contractions up to 60% of maximal force were unaffected (all P-values > 0.4). Long-distance running impaired the capacity to quickly produce force in ballistic contractions of maximal, but not of submaximal, amplitudes. Overall, these findings suggest that central and peripheral fatigue do not affect the quickness to which muscle contracts across a wide range of submaximal forces. This is a relevant finding for running and other daily life activities that rely on the production of rapid submaximal contractions rather than maximal force levels.

Peg-manipulation capabilities of middle-aged adults have a greater influence on pegboard times than those of young and old adults

Declines in manual dexterity are frequently quantified as the time it takes to complete the grooved pegboard test. The test requires individuals to manipulate 25 pegs, one at a time, by removing them from a well and inserting them into a prescribed hole. The manipulation of each peg involves four phases: selection, transport, insertion, and return. The purpose of our study was to compare the times to complete the four phases of peg manipulation and the forces applied to the pegboard during peg insertion as young, middle-aged, and old adults performed the grooved pegboard test. The relative significance of the peg-manipulation attributes for 30 young (24.0 ± 4.4 years), 15 middle-aged (46.5 ± 6.5 years), and 15 old (70.4 ± 4.0 years) adults was assessed with a multiple-regression analysis. The grooved pegboard test was performed on a force plate. Pegboard times for the old adults (81 ± 17 s) were longer than those for young (56 ± 7 s) and middle-aged (58 ± 11 s) adults. Regression analysis indicated that the explanatory variables for the pegboard times of young (R² = 0.33) and middle-aged (R² = 0.78) adults were the times for the peg insertion and return phases, whereas the predictors for old adults (R² = 0.49) were the times for the peg selection and transport phases. The relative influence of peg-manipulation capabilities on a pegboard test of manual dexterity was greater for middle-aged adults than for young and old adults.