Fatigability of the dorsiflexors and associations among multiple domains of motor function in young and old adults

Justice, Jamie N.; Mani, Diba; Pierpoint, Lauren A.; Enoka, Roger M.

doi:10.1016/j.exger.2014.03.018

Cited by 40 publications

(37 citation statements)

References 59 publications

(78 reference statements)

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“…In contrast to the absence of an association between walking endurance and the test of performance fatigability used by Justice et al (30), another measure of fatigue has been found to be associated with walking endurance in old adults. In a sample of 1,155 adults (65-102 yrs), Vestergaard et al (70) examined the association between fatigue and physical function by categorizing participants into those who self-reported elevated levels of fatigue and those who did not.…”

Section: Human Performance and Fatiguecontrasting

confidence: 62%

“…Given that walking endurance provides a clinically relevant measure of human performance, Justice et al (30) compared the associations between walking endurance and measures of neuromuscular function in young (22 ± 4 yrs) and old (75 ± 6 yrs) adults. Of particular interest was the strength of the association between walking endurance (500-m walk) and a laboratory test of leg-muscle fatigability.…”

Section: Human Performance and Fatiguementioning

confidence: 99%

“…In a subsequent analysis of the data reported by Justice et al (30), the outcome measures were entered into a stepwise, multiple-regression model to predict the variance in 500-m walk time for each group of participants. Separate models emerged for young and old adults, with more of the variance explained for young adults (R 2 = 0.42) than for old adults (R 2 = 0.31; Figure 4).…”

Section: Human Performance and Fatiguementioning

confidence: 99%

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Translating Fatigue to Human Performance

Enoka

Duchateau

2016

Medicine &Amp; Science in Sports &Amp; Exercise

Self Cite

603

582

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Despite flourishing interest in the topic of fatigue—as indicated by the many presentations on fatigue at the 2015 annual meeting of the American College of Sports Medicine—surprisingly little is known about its impact on human performance. There are two main reasons for this dilemma: (1) the inability of current terminology to accommodate the scope of the conditions ascribed to fatigue, and (2) a paucity of validated experimental models. In contrast to current practice, a case is made for a unified definition of fatigue to facilitate its management in health and disease. Based on the classic two-domain concept of Mosso, fatigue is defined as a disabling symptom in which physical and cognitive function is limited by interactions between performance fatigability and perceived fatigability. As a symptom, fatigue can only be measured by self-report, quantified as either a trait characteristic or a state variable. One consequence of such a definition is that the word fatigue should not be preceded by an adjective (e.g., central, mental, muscle, peripheral, and supraspinal) to suggest the locus of the changes responsible for an observed level of fatigue. Rather, mechanistic studies should be performed with validated experimental models to identify the changes responsible for the reported fatigue. As indicated by three examples (walking endurance in old adults, time trials by endurance athletes, and fatigue in persons with multiple sclerosis) discussed in the review, however, it has proven challenging to develop valid experimental models of fatigue. The proposed framework provides a foundation to address the many gaps in knowledge of how laboratory measures of fatigue and fatigability impact real-world performance.

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Section: Human Performance and Fatiguecontrasting

confidence: 62%

Section: Human Performance and Fatiguementioning

confidence: 99%

Section: Human Performance and Fatiguementioning

confidence: 99%

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Translating Fatigue to Human Performance

Enoka

Duchateau

2016

Medicine &Amp; Science in Sports &Amp; Exercise

Self Cite

603

582

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“…Consequently, while fatigue does negatively impact on various metrics of balance and posture 5,39,40 , these changes are time-dependent and can tend to dissipate quickly. This raises the possibility that a contributing factor to the increased falls risk in the older adults may be their decreased ability to recover as quickly from the fatiguing intervention as individuals in the other (younger) groups 41,42 . Thus, while all subjects may exhibit declines in function immediately post-exercise, it is the time-course of the recovery period, which may be a determining factor in whether these declines translate to a prolonged increase in falls risk.…”

Section: Discussionmentioning

confidence: 99%

Walking-Induced Fatigue Leads to Increased Falls Risk in Older Adults

Morrison

Colberg

Parson

et al. 2016

Journal of the American Medical Directors Association

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Background For older adults, falls are a serious health problem with over 30% of people over 65 suffering a fall at least once a year. One element often overlooked in the assessment of falls is whether a person’s balance, walking ability and overall falls risk is affected by performing activities of daily living such as walking. Objective This study assessed the immediate impact of incline walking at a moderate pace on falls risk, leg strength, reaction time, gait and balance in 75 healthy adults from 30 to 79 years of age. Subjects were subdivided into five equal groups based upon their age (Group 1, 30–39 years; Group 2, 40–49 years; Group 3, 50–59 years; Group 4, 60–69 years; Group 5, 70–79 years). Methods Each person’s falls risk (using the Physiological Profile Assessment), simple reaction time, leg strength, walking ability and standing balance were assessed prior to and following a period of incline walking on an automated treadmill. The walking task consisted of three 5-minute trials at a faster than preferred pace. Fatigue during walking was elicited by increasing the treadmill incline in increments of 20 (from level) every minute to a maximum of 80. Results As predicted, significant age-related differences were observed prior to the walking activity. In general, increasing age was associated with declines in gait speed, lower limb strength, slower reaction times and increases in overall falls risk. Following the treadmill task, older adults exhibited increased sway (path length 60–69 yrs; 10.2±0.7 to 12.1±0.7 cm: 70–79 yrs; 12.8±1.1 to 15.1±0.8 cm), slower reaction times (70–79 yrs; 256±6 to 287±8 ms), and declines in lower limb strength (60–69 yrs; 36±2 to 31±1 kg: 70–79 yrs; 32.3±2 to 27±1 kg). However, a significant increase in overall falls risk (pre; 0.51±0.17: post; 1.01±0.18) was only seen in the oldest group (70–79 years). For all other persons (30–69 years), changes resulting from the treadmill-walking task did not lead to a significant increase in falls risk. Conclusions As most falls occur when an individual is moving and/or fatigued, assessing functional properties related to balance, gait, strength and falls risk in older adults both at rest and following activity may provide additional insight.

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“…Despite the age-related decline in these various parameters, repeated muscular activation does not always lead to greater fatigability in older adults when compared with young adults, and seems to depend on the task. During sustained isometric tasks, older adults are usually less fatigable than young adults (Christie et al 2011), until more advanced ages (Justice et al 2014). However, there are far fewer studies focusing on age-related fatigability for dynamic as compared with isometric contractions.…”

Section: Introductionmentioning

confidence: 99%

Older men are more fatigable than young when matched for maximal power and knee extension angular velocity is unconstrained

Dalton

Power

Paturel

et al. 2015

AGE

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The underlying factors related to the divergent findings of age-related fatigue for dynamic tasks are not well understood. The purpose here was to investigate age-related fatigability and recovery between a repeated constrained (isokinetic) and an unconstrained velocity (isotonic) task, in which participants performed fatiguing contractions at the velocity (isokinetic) or resistance (isotonic) corresponding with maximal power. To compare between tasks, isotonic torque-power relationships were constructed prior to and following both fatiguing tasks and during short-term recovery. Contractile properties were recorded from 9 old (~75 years) and 11 young (~25 years) men during three testing sessions. In the first session, maximal power was assessed, and sessions 2 and 3 involved an isokinetic or an isotonic concentric fatigue task performed until maximal power was reduced by 40 %. Compared with young, the older men performed the same number of contractions to task failure for the isokinetic task (~45 contractions), but 20 % fewer for the isotonic task (p<0.05). Regardless of age and task, maximal voluntary isometric contraction strength, angular velocity, and power were reduced by~30,~13, and~25 %, respectively, immediately following task failure, and only isometric torque was not recovered fully by 10 min. In conclusion, older men are more fatigable than the young when performing a repetitive maximal dynamic task at a relative resistance (isotonic) but not an absolute velocity (isokinetic), corresponding to maximal power.

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Fatigability of the dorsiflexors and associations among multiple domains of motor function in young and old adults

Cited by 40 publications

References 59 publications

Translating Fatigue to Human Performance

Translating Fatigue to Human Performance

Walking-Induced Fatigue Leads to Increased Falls Risk in Older Adults

Older men are more fatigable than young when matched for maximal power and knee extension angular velocity is unconstrained

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