Comparisons of changes in the two-point discrimination test following muscle fatigue in healthy adults

Feasibility and Usefulness of Repetitions-In-Reserve Scales for Selecting Exercise Intensity: A Scoping Review

The intensity of resistance training (RT) exercise is an important consideration for determining relevant health and performance-related outcomes. Yet, current objective exercise intensity measures present concerns in terms of viability or cost. In response to these concerns, repetition-in-reserve (RIR) scales may represent an adequate method of measuring and regulating intensity. However, no recent review has focused on how RIR scales have been used for this purpose in prior research. We prepared the present scoping review to analyze the feasibility and usefulness of RIR scales in selecting RT intensity. We conducted a systematic search in PubMed, SPORTDiscus, PsycINFO, and ClinicalTrials.gov databases (last search date April 2023) for experimental and non-experimental studies that utilized an RIR scale to measure proximity to failure in RT activities with apparently healthy individuals of any age. We qualitatively analyzed 31 studies (N = 855 mostly male adult participants) published between 2012-2023. RIR scales appeared to be contextually feasible and useful in prescribing and adjusting RT intensity. The most common trend in this research was to prescribe a target RIR and adjust the exercise load for a desired proximity to muscle failure. Additionally, when measuring proximity to failure as an outcome of interest, the literature suggests that the RIR prediction should be made close to task failure to increase its accuracy. Future research should further explore the impact of sex, RT experience, exercise selection, and muscle conditioning on the overall RIR approach.

Examination of foot sensations in children with generalized joint hypermobility

BACKGROUND

Generalized joint hypermobility (GJH) is a condition that can be observed in children and children with GJH may have problems such as clumsiness, proprioceptive sensory loss, balance and coordination disorders.

AIMS

To evaluate foot and ankle senses in children with GJH and compare them with their healthy peers.

STUDY DESIGN

A cross-sectional study.

SUBJECTS

Children aged 5-14 years with and without GJH were included in the study.

OUTCOME MEASURES

After assessing the joint hypermobility of the children with the Beighton Score, tactile, vibration, two-point discrimination, and proprioception senses were evaluated.

RESULTS

A total of 40 children (15 females, 25 males, mean age 9.43 years, SD ± 2.98 years, 20 with GJH and 20 without GJH) were included in the study. In children with GJH, foot sole tactile sense and ankle dorsiflexion and plantar flexion joint position sense were deficient in comparison with healthy controls (p < 0.05).

CONCLUSIONS

There were deficiencies in foot and ankle tactile and proprioceptive senses in children with GJH. Neurosensorimotor examination of balance and coordination should be performed and appropriate intervention programs should be planned accordingly in children with GJH.

The Influence of Muscular Strength and Local Muscular Endurance on Accuracy of Estimated Repetitions to Failure in Resistance-Trained Males

This study investigated whether muscular strength and local muscular endurance (LME) influences accuracy of estimated repetitions to failure (ERF) during resistance exercise. Twenty resistance-trained males (age 26.3 ± 6.9 years) completed five sets of 10 repetitions at 70% 1RM for the bench press and squat. Following the 10th repetition of each set, participants reported ERF and then continued to concentric failure. Participants were separated into one of two groups based on muscular strength and LME. There were no significant differences between strength groups for error in ERF, ERF, and actual repetitions to failure (ARF). High-LME compared to Low-LME had greater ERF for all sets of bench press (p < 0.05) and two sets of squat (p < 0.05). Greater ARF was observed in High-LME for two of five sets for bench press (p < 0.05) and squat (p < 0.05). High-LME had greater error in ERF for bench press set 1 (p < 0.01) and set 4 (p = 0.04), while for set 1 only for squat (p = 0.01). Findings indicate that LME influences accuracy of ERF during the initial set of bench press and squat as well as a latter set for the bench press. Future studies with larger sample sizes are warranted to explore whether LME affects accuracy of ERF across multiple sets.

Two-point discrimination assessment of the lower extremities of healthy young Turkish individuals

OBJECTIVES

To investigate the normative two-point discrimination (TPD) values of the lower extremities of healthy young Turkish individuals.

PATIENTS AND METHODS

Fifty-five healthy, young adults were recruited in this prospective study. Ten lower extremity parts were tested with esthesiometer: proximal thigh, midlateral thigh, midmedial thigh, midposterior thigh, proximal lateral leg, distal lateral leg, medial leg, the tip of great toe, skin over 1-2 metatarsal interspace, skin over 5th metatars at both dominant and non-dominant sides.

RESULTS

There were 27 (49.1%) female and 28 (50.9%) male participants with a mean age of 22.06 ± 1.76 years. The reference values of the TPD of the lower extremities were between 42.4 ± 5.4 mm and 4.0 ± 1.3 mm by females and between 42.6 ± 6.4 mm and 4.4 ± 2.4 mm by males. Test values in the combined group of men and women were statistically greater at the dominant sides than the non-dominant sides at the following areas: proximal lateral leg (p = 0.01), distal lateral leg (p = 0.046), medial leg (p = 0.001), tip of great toe (p = 0.02), skin over 1-2 metatarsal interspace (p = 0.010), skin over 5th metatars (p = 0.002). There was no statistical difference in the test scores of men and women in any of the measured areas, with additional evaluation of both the dominant and the non-dominant sides (p > 0.05).

CONCLUSION

The results of the present study demonstrated that TPD ability varied in different skin areas within the same individual. We found that laterality, though with lower scores on the non-dominant side in some lower extremity parts, but not the gender had an effect on TPD.

Immediate Effect of Local Vibration Therapy for Sport-induced Fatigue Based on Traditional Chinese Medicine's Holistic Theory

Introduction

Vibration therapy has been widely used and published in alleviating muscle fatigue. However, reports on applying vibration therapy based on the holisitic theory of traditional Chinese medicine (TCM) remains limited. This study is to evaluate the immediate effect of vibration therapy on exercise-induced muscle fatigue.

Methods

For this retrospective parallel controlled study, all data were from a previously approved and completed clinical trial. Participants (n=40) in the clinical trial included local Greco-Roman wrestling and Judo athletes in south China. The participants were equally randomly divided into the intervention group (n=20) and control group (n=20). The intervention group received a seven-week vibration intervention-based TCM holistic theory combined with conventional therapy, such as stretching, massage, and flapping, while the control group only received the conventional therapy. Surface electromyography (sEMG) of the lumbar segment of erector spinae was measured for each participant pre- and postintervention, and the two-point discrimination thresholds of the data were differentiated and compared with panel data analysis.

Results

For the control group, the pre- and postintervention sEMG measure showed no significant difference (p=0.333), whereas significant difference (p=0.004) was observed for the intervention group. Further, the pre- and postintervention two-point discrimination test also showed a significant difference (p=0.016) for the intervention group.

Discussion

The application of vibration therapy based on TCM holistic theory may have an immediate effect in reducing sport-induced muscle fatigue from intensive training. Future larger sample size and robust designed clinical trial is warranted to evaluate the long-term effect of the intervention.

Similar effects of fatigue induced by a repetitive pointing task on local and remote light touch and pain perception in men and women

Background

Women involved in repetitive, fatiguing, jobs develop more neck and/or shoulder musculoskeletal disorders than men. Sex differences in the pain response to exercise could contribute to the higher prevalence of neck/shoulder musculoskeletal disorders in women. The objective of this study was to assess sex differences in pain sensitivity following a fatiguing upper limb task. Relationships between measures of fatigue and of the sensitivity to nociceptive and to non-nociceptive stimulations were also explored.

Methods

Thirty healthy adults (15 women) performed a fatiguing repetitive pointing task with their dominant arm. Upper limb electromyography was recorded from the dominant upper trapezius, anterior deltoid and bicep brachii and from the contralateral tibialis anterior. Before and immediately after the repetitive pointing task, pressure pain and light touch sensitivity thresholds were measured over the same muscles.

Results

Electromyographic signs of fatigue were observed only in the anterior deltoid and biceps brachii muscles. Pressure pain thresholds over both muscles increased slightly (effect size ≤ 0.34), but no changes occurred over the upper trapezius and the tibialis anterior. Light touch thresholds increased moderately to importantly after the repetitive pointing task over all four muscles (effect sizes = 0.58 to 0.87). No sex differences were observed in any sensory variable. Moreover, no or weak correlations (r = -0.27 to 0.39) were observed between electromyographical signs of fatigue, light touch threshold and pressure pain threshold variables.

Conclusions

We observed sex-independent effects of a repetitive upper limb task on the sensitivity to painful and to nonpainful stimuli. Moreover, the hypoalgesia induced by the repetitive pointing task was weak and localized, and did not directly correlate with the induced muscle fatigue. Results suggest that fatigue-related changes in the sensitivity to noxious and innocuous stimuli could not explain women’s greater prevalence of neck/shoulder musculoskeletal disorders.

Effects of old age on fatigability and sensorimotor characteristics of a repetitive upper limb fatiguing task

Objectives

1) Determine the effects of old age on sensorimotor responses to a fatiguing work-like task. 2) Explore how old age influences the relationships between task fatigability, everyday perceptions of fatigability, and sensorimotor function.

Methods

Healthy young (N = 17, 9W) and older (N = 13, 10W) adults completed the Pittsburgh Fatigability Scale to assess everyday perceptions of physical (PF) and mental fatigability and performed a repetitive tapping task to fatigue. Before and after the task, grip strength was assessed using a hand-grip dynamometer and touch-pressure sensitivity was measured (shoulder, hand) using Semmes-Weinstein monofilaments.

Results

Older, but not young adults, had increased touch-pressure sensitivity at the shoulder after fatigue (interaction, p = 0.007). No changes in grip strength were observed (p>0.05). Task fatigability was not different between young and old adults (p>0.05). Having less task fatigability was associated with lower PF, higher grip strength, and higher touch-pressure sensitivity at the hand (ρ = 0.37–0.58, p<0.05), with the hand sensation association also observed in the old adult subgroup (ρ = 0.56, p = 0.046).

Conclusions

With old age, there were fatigue-related alterations to sensory but not physical function. While task fatigability was associated with perceptual, physical, and sensory features, sensory features appear to have a more important role with old age.

Widespread impairment of tactile spatial acuity and sensory-motor control in patients with chronic nonspecific neck pain with neuropathic features

OBJECTIVE

To assess differences in tactile spatial acuity and in sensory-motor control between patients with chronic nonspecific neck pain (CNSNP) with and without neuropathic features (NF), as well as asymptomatic.

METHODS

183 participants were included, 135 had CNSNP classified by the Self-report version of Leeds Assessment of Neuropathic Symptoms and Signs scale in order to identify pain with NF: (1) CNSNP with NF (n = 67), (2) CNSNP with No-NF (n = 68), and (3) asymptomatic subjects (n = 48). The following tests in the following order were assessed after determining the participants' clinical characteristics: 1) two-point discrimination, 2) joint position error, and 3) craniocervical flexion test.

RESULTS

Both neck pain groups showed a significant reduction in their ability to discriminate two points in the trapezium and masseter, as well as a significant deficit of a moderate to large magnitude in craniocervical motor control compared with the asymptomatic group. However, only the CNSNP with NF group showed a significant impairment of the two-point discrimination in the tibia (d = 0.57) and a significant impairment of the kinesthetic sense (neck rotation, d = 0.73; neck lateroflexion, d = 0.69), compared with the asymptomatic group. Significant differences in pain intensity, disability and psychological factors between the CNSNP groups were also found, observing the poorest results in the NF group.

CONCLUSIONS

Patients with CNSNP with NF have a greater sensory, motor and psychological impairment than those without NF, more pain intensity, disability and negative psychological factors, as well as more impaired tactile spatial acuity in areas remote to the pain and impaired cervical kinesthetic sense.

Associations between Perceptual Fatigue and Accuracy of Estimated Repetitions to Failure during Resistance Exercises

The ability to accurately identify proximity to momentary failure during a set of resistance exercise might be important to maximise training adaptations. This study examined the association between perceptual fatigue and the accuracy of the estimated repetitions to failure (ERF). Twenty-seven males and eleven females performed sets of 10 repetitions at specific loads for the chest press and leg-press. Following the completion of 10 repetitions, participants rated their fatigue and ERF and then proceeded to concentric failure (actual repetitions to failure) to determine the ERF accuracy (i.e., error-ERF). Small correlations were found between perceptual fatigue and error-ERF for the chest-press (r = -0.26, p = 0.001) and the leg-press (r = -0.18, p = 0.013). For actual repetitions to failure and error-ERF, a strong correlation was found for the chest-press (r = 0.68, p < 0.001) and a very strong correlation was foundfor the leg-press (r = 0.73, p < 0.001). Moderate correlations were found between perceptual fatigue and actual repetitions to failure for the chest-press (r = -0.42, p < 0.001) and leg-press (r = -0.40, p < 0.001). Overall, findings suggest that the accuracy of the estimated repetitions to failure is more strongly associated with proximity to task repetition failure rather than subjective feelings of fatigue.

Accuracy in Estimating Repetitions to Failure During Resistance Exercise

Hackett, DA, Cobley, SP, Davies, TB, Michael, SW, and Halaki, M. Accuracy in estimating repetitions to failure during resistance exercise. J Strength Cond Res 31(8): 2162-2168, 2017-The primary aim of this study was to assess the accuracy in estimation of repetitions to failure (ERF) during resistance exercise. Furthermore, this investigation examined whether the accuracy in ERF was affected by training status, sex, or exercise type. Eighty-one adults (men, n = 53 and women, n = 28) with broad range of resistance training experience participated in this study. Subjects performed up to 10 sets of 10 repetitions at 70% 1 repetition maximum (1RM) and 80% 1RM for the chest press and leg press, respectively. At the completion of each set, subjects reported their ERF and then continued repetitions to failure to determine actual repetitions to failure (ARF). The accuracy (amount of error) of ERF was determined over an ARF 0-10. Significant differences were found for error of ERF among ARF (p < 0.001), with the error of ERF ∼1 repetition at ARF 0-5 compared with >2 repetitions at ARF 7-10. Greater accuracy was found for the chest press compared with leg press, with the error of ERF ≤1 repetition for ARF 0-5 and ARF 0-3, respectively (p = 0.012). Men were found to be more accurate than women at specific ARFs for the leg press (p = 0.008), whereas no interaction was found for the chest press. Resistance training experience did not affect the accuracy in ERF. These results suggest that resistance trainers can accurately estimate repetitions to failure when close to failure and that ERF could importantly be practically used for prescription and monitoring of resistance exercise.

Therapeutic effects of massage and electrotherapy on muscle tone, stiffness and muscle contraction following gastrocnemius muscle fatigue

[Purpose] This study aimed to examine the effects of a combined intervention consisting of massage therapy and transcutaneous electrical nerve stimulation on gastrocnemius muscle fatigue, assessing whether the intervention improved muscle tone, stiffness, and muscle contraction. [Subjects and Methods] The subjects were 20 healthy males in their 20s who were equally divided into a transcutaneous electrical nerve stimulation group and a combined therapy group that received a combination of massage therapy and transcutaneous electrical nerve stimulation. Muscle fatigue was triggered on the gastrocnemius muscle, and the effects of intervention method on muscle tone, stiffness, and muscle contraction were examined over time. [Results] Lateral and medial gastrocnemius muscle tone and stiffness significantly increased and gastrocnemius muscle contraction significantly decreased in each group immediately after fatigue was triggered on the gastrocnemius muscle. There was no difference in the effects of the two intervention methods over time. [Conclusion] This study verified that a combined therapy of massage therapy and transcutaneous electrical nerve stimulation was able to be used effectively in improving muscle tone, stiffness, muscle contraction, thereby reducing gastrocnemius muscle fatigue.

Two-point discrimination of the upper extremities of healthy Koreans in their 20's

[Purpose] The present study attempted to measure two-point discrimination in the upper extremities of healthy Koreans in their 20's. [Subjects and Methods] Using a three-point esthesiometer, we conducted an experiment with a group of 256 college students (128 male and 128 female), attending N University in Chonan, Republic of Korea. [Results] Females showed two-point discrimination at a shorter distance than males at the following points: (i) 5 cm above the elbow joint, the middle part, and 5 cm below the shoulder joint of the anterior upper arm; (ii) 5 cm above the elbow joint and 5 cm below the shoulder joint of the posterior upper arm; (iii) 5 cm above the front of the wrist joint of the forearm; 5 cm below the elbow joint, the palmar part of the distal interphalangeal joint of the thumb, the dorsal part of the distal interphalangeal joint of the middle and little fingers. It was also found that females showed greater two-point discrimination than males in distal regions rather than proximal regions. [Conclusion] The findings of this study will help establish normal values for two-point discrimination of upper extremities of young Koreans in their 20's.