Kurt Jackson

Acute Effects of Whole-Body Vibration on Lower Extremity Muscle Performance in Persons With Multiple Sclerosis

Background and Purpose: Whole-body vibration (WBV) is a relatively new form of exercise training that may influence muscle performance. This study investigated the acute effects of high- (26 Hz) and low- (2 Hz) frequency WBV on isometric muscle torque of the quadriceps and hamstrings in persons with multiple sclerosis. Participants and Method: Fifteen individuals (mean age = 54.6 years, SD = 9.6) with multiple sclerosis and Expanded Disability Status Scale scores ranging from 0 to 6.5 (mean = 4.2, SD = 2.3) participated in this randomized, crossover study. After baseline measures of isometric quadriceps and hamstring muscle torque, subjects were exposed to 30 seconds of WBV at either 2 or 26 Hz. Torque values were measured again at one, 10, and 20 minutes after vibration. Subjects returned one week later to repeat the same protocol at the alternate vibration frequency. Results: There were no significant differences in isometric torque production between the 2- and 26-Hz WBV conditions. There was also no significant difference between baseline torque values and those measured at one, 10, and 20 minutes after either vibration exposure. However, there was a consistent trend of higher torque values after the 26-Hz WBV when compared with the 2-Hz condition for both quadriceps and hamstring muscles. Discussion and Conclusion: Although not statistically significant, peak torque values for both quadriceps and hamstring muscles were consistently higher after 30 seconds of WBV at 26 vs 2 Hz. Whether WBV presents a viable treatment option as either a warm-up activity or a long-term exercise intervention is yet to be determined. Future studies should include a wider variety of WBV parameters and the use of functional outcome measures.

A group kickboxing program for balance, mobility, and quality of life in individuals with multiple sclerosis: a pilot study.

Background and Purpose: Balance and mobility impairments are common in individuals with multiple sclerosis (MS). The primary purpose of this pilot study was to evaluate the feasibility of a 5-week group kickboxing program and to measure changes in balance, mobility, and quality of life in individuals with MS associated with this training. Methods: This single-group repeated-measures study involved a convenience sample of 15 individuals with MS who had minimal to moderate levels of disability and were recruited from the community. Eleven participants completed all phases of testing and training. The intervention was a 5-week group kickboxing program performed 3 times per week. Outcome measures were assessed 5 weeks prior to the intervention, 1 week prior to the intervention, and within 1 week of completing the intervention. Outcome measures include gait speed, Timed Up & Go test, Berg Balance Scale, Dynamic Gait Index, Mini-BESTest, Activities Specific Balance Confidence scale, and the Multiple Sclerosis Quality of Life Survey. Results: There were significant improvements in gait speed, some clinical measures of balance, and balance confidence following the intervention but no changes were observed in health-related quality of life. There were no unanticipated adverse events and compliance was high. Conclusion: Group kickboxing appears to be a feasible exercise activity for individuals with MS that may lead to improvement in select measures of balance and mobility. However, the clinical relevance of these findings is yet to be determined. Further investigation of this novel intervention may be warranted.

Effects of Heat Stress and Sex on Pacing in Marathon Runners

Abstract Trubee, NW, Vanderburgh, PM, Diestelkamp, WS, and Jackson, KJ. Effects of heat stress and sex on pacing in marathon runners. J Strength Cond Res 28(6): 1673–1678, 2014—Recent research suggests that women tend to exhibit less of a precipitous decline in run velocity during the latter stages of a marathon than men when the covariates of age and run time are controlled for. The purpose of this study was to examine this sex effect with the added covariate of heat stress on pacing, defined as the mean velocity of the last 12.2 km divided by the mean velocity of the first 30 km. A secondary purpose of this investigation was to compare the pacing profiles of the elite men and women runners and the pacing profiles of the elite and nonelite runners. Subjects included 22,990 men and 13,233 women runners from the 2007 and 2009 Chicago marathons for which the mean ambient temperatures were 26.67° C and 2.77° C, respectively. Each 5-km split time was measured via an electronic chip worn on the participants’ shoe. Multiple regression analysis indicated that age, sex, heat stress, and overall finish time (p < 0.01 for each) were simultaneous independent elements of pacing. Nonelite women were consistently better pacers than nonelite men in both marathons, and this sex difference was magnified from cold to warm race temperatures. No difference (p < 0.05) in pacing was found between elite men and women runners. Elite men and women had enhanced pacing over their nonelite counterparts. In hotter temperatures, coaches of novice runners should advise their athletes to implement a slower initial velocity to maintain or increase running velocity later in the race.

Feasibility and effects of a group kickboxing program for individuals with multiple sclerosis: A pilot report

BACKGROUND AND PURPOSE Balance and mobility impairments are common in persons with multiple sclerosis (MS). The primary purpose of this pilot program was to evaluate the feasibility and the effects of group kickboxing on balance and mobility in individuals with MS. METHODS Four individuals with relapsing-remitting or secondary progressive MS participated in a group kickboxing program two times per week for 8 weeks. Outcome measures included the Berg Balance Scale (BBS), Dynamic Gait Index (DGI), Timed Up and Go (TUG), walking speed and the Activities Specific Balance Confidence Scale (ABC). RESULTS Following training, 3 of 4 participants had improvements in BBS performance. All participants demonstrated improvements in the DGI. Changes in the TUG, ABC, and walking speed were more variable. CONCLUSION Group kickboxing appears to be a feasible exercise activity for individuals with MS and may lead to improvement in select measures of balance. Further investigation may be warranted.

Measures of Balance Performance Are Affected by a Rested Versus Fatigued Testing Condition in People With Multiple Sclerosis

To investigate the effects of a rested and fatigued testing condition on measures of balance in people with multiple sclerosis (MS).

Using Posturography to Examine the Immediate Effects of Vestibular Therapy for Children with Autism Spectrum Disorders: A Feasibility Study

ABSTRACT Aims: The primary objective of this study was to determine the feasibility of using posturography to monitor acute changes in postural control induced by a Sensory Integration (SI) therapy intervention. A secondary objective was to identify which posturography outcome parameters, tests conditions and data analysis methods might be most useful in identifying post-intervention changes. Methods: Five children with Autism Spectrum Disorder (ASD) and five children with typical development (TD) participated in a 10 min vestibular swing activity and had their postural stability evaluated pre- and post-intervention under four different sensory testing conditions. Sway ranges, mean sway velocity, sway root mean square (RMS), and sample entropy were calculated from center of pressure (COP) data. Results: All five children with ASD demonstrated decreased mean sway velocity in the eyes open/flat plate condition post-intervention with an average decrease of 5.87 ± 2.69 mm/s. Four of the five children with ASD demonstrated an increase in RMS and a decrease in anterior/posterior sample entropy post-intervention in the eyes closed, foam pad condition and eyes open, flat plate condition respectively. Conclusion: Posturography may be useful for assessing acute physiologic responses to an SI therapy intervention and warrants further investigation.

A Home-based Exercise Program for the Foot and Ankle to Improve Balance, Muscle Performance and Flexibility in Community Dwelling Older Adults: A Pilot Study

Background and purpose: Strength and range of motion of the foot and ankle have been shown to be related to measures of balance and fall risk in older adults. The primary purpose of this pilot investigation was to evaluate the feasibility of a 6-week home-based exercise program focusing on the foot and ankle and any associated changes in balance, muscle performance and range of motion in older adults. Methods: This single-group repeated measures study involved a convenience sample of 21 healthy communitydwelling older adults age 60-90. Nineteen participants completed all phases of the testing and training. The intervention was a 6-week home-based exercise program focusing on ankle musculature performed 3 times per week. Outcome measures were assessed on three separate occasions: baseline, pre-intervention, and post-intervention. Outcome measures included the Mini-Balance Evaluation Systems Test (Mini-BESTest), gait speed, Timed Up and Go (TUG), Activities Specific Balance Confidence Scale (ABC), gastrocnemius muscle strength and ankle dorsiflexion range of motion. Results: Following the intervention, there were significant improvements in the Mini-BESTest, gait speed, TUG, gastrocnemius strength and ankle dorsiflexion range of motion. There was also significant positive relationship between improvements in the Mini-BESTest and gastrocnemius strength. There were no unanticipated adverse events and compliance was high. Conclusions: A simple but progressive home-based exercise program for the foot and ankle appears to be feasible for older individuals and may lead to meaningful improvements in measures of balance and mobility. Further research of this targeted intervention may be warranted.

Systematically Controlling for the Influence of Age, Sex, Hertz and Time Post-Whole-Body Vibration Exposure on Four Measures of Physical Performance in Community-Dwelling Older Adults: A Randomized Cross-Over Study

Though popular, there is little agreement on what whole-body vibration (WBV) parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (N = 32). Participants were exposed to 2 min WBV per session at either 2 Hz or 26 Hz and outcome measures were recorded at 2, 20 and 40 min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2 Hz and 26 Hz treatments (P ≤ 0.05) and showed statistically significant interactions between age and gender (P ≤ 0.01). Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2 Hz and 26 Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2 Hz and 26 Hz exert a treatment effect.

Use of an elliptical machine for improving functional walking capacity in individuals with chronic stroke: a case series.

Background and Purpose: Decreased functional walking capacity is a common consequence of stroke. Identifying practical and cost-effective methods to improve walking in individuals with stroke is an important goal of rehabilitation professionals. Participants: Participants were 3 men with chronic (>6 month) stroke, who could walk on level surfaces either without an assistive device or with a single-point cane. Intervention: Participants trained 2 to 3 times per week for 8 weeks, using an elliptical machine. The training target was 20 minutes of uninterrupted training, while maintaining predetermined parameters of heart rate and perceived exertion. Outcomes: Outcome measures assessed before and after training included habitual and fast gait speed, 6-minute walk test (6MWT), Timed “Up & Go” test, and Berg Balance Scale. Following training there was no change in walking speed. There was no change in 6MWT performance for participants 1 and 2. While participant 3 showed a 25% improvement in 6MWT, this change did not meet the minimal detectable change for walking speed in individuals with stroke. All participants demonstrated improved Berg Balance Scale performance (9%-28%), with participant 1 exceeding the minimal detectable change in this measure. Timed Up & Go test performance improved by 5% to 15% in all participants. Discussion: Elliptical training appears to be a safe and feasible training alternative for ambulatory individuals with chronic stroke. Training 2 to 3 days per week resulted in no improvements in walking speed; however, participants did demonstrate variable improvements in endurance, balance, and functional mobility. It is possible that a higher training frequency and/or training speed are required to influence walking performance in individuals who are ambulatory. Equipment design, principles of exercise prescription, and participant characteristics should be considered when selecting elliptical training as an intervention.

The Effects of Backwards Running Training on Forward Running Economy in Trained Males.

Abstract Ordway, JD, Laubach, LL, Vanderburgh, PM, and Jackson, KJ. The effects of backwards running training on forward running economy in trained males. J Strength Cond Res 30(3): 763–767, 2016—Backwards running (BR) results in greater cardiopulmonary response and muscle activity compared with forward running (FR). BR has traditionally been used in rehabilitation for disorders such as stroke and lower leg extremity injuries, as well as in short bursts during various athletic events. The aim of this study was to measure the effects of sustained backwards running training on forward running economy in trained male athletes. Eight highly trained, male runners (26.13 ± 6.11 years, 174.7 ± 6.4 cm, 68.4 ± 9.24 kg, 8.61 ± 3.21% body fat, 71.40 ± 7.31 ml·kg−1·min−1) trained with BR while harnessed on a treadmill at 161 m·min−1 for 5 weeks following a 5-week BR run-in period at a lower speed (134 m·min−1). Subjects were tested at baseline, postfamiliarized, and post-BR training for body composition, a ramped V[Combining Dot Above]O2max test, and an economy test designed for trained male runners. Subjects improved forward running economy by 2.54% (1.19 ± 1.26 ml·kg−1·min−1, p = 0.032) at 215 m·min−1. V[Combining Dot Above]O2max, body mass, lean mass, fat mass, and % body fat did not change (p > 0.05). Five weeks of BR training improved FR economy in healthy, trained male runners without altering V[Combining Dot Above]O2max or body composition. The improvements observed in this study could be a beneficial form of training to an already economical population to improve running economy.