Neuromuscular Fatigability Associated With Different Pacing Strategies During an Ultra-Endurance Pull-Up Task: A Case Study

International Journal of Exercise Science 15(3): 1514-1527, 2022. While neuromuscular fatigability has been previously characterized after running and cycling, no study has investigated an ultra-endurance upper body task. In preparation for a world record attempt, three pacing strategies to perform 1980 pull-ups in 6 hrs were compared during independent sessions: fast pace, long recovery (FL), fast pace, multiple short recoveries (FMS), and slow pace, no recovery (SN). Elbow flexion maximal voluntary contraction (MVC) force, grip strength, peripheral fatigue, and biceps brachii electromyography were quantified every 330 pull-ups and during recovery, alongside heart rate, perceived effort, and arm muscle pain. In all conditions, MVC force decreased rapidly within the first set of 330 pull-ups, with the greatest depression observed in FL (-29.1%) and more gradual declines in FMS (-18.6%) and SN (-8.6%). Similarly, FL displayed the greatest decline in potentiated single twitch (FL: -75.0%; FMS: -53.9%; SN: -41.8%) and high-frequency doublet forces (FL: -63.3%; FMS: -29.2%; SN: -41.8%) following the first set, as well as higher heart rate, effort, and pain throughout the task. Following 24 hrs, MVC force recovered slowest in FL and grip strength recovered fastest in SN. Therefore, for the world record attempt, a strategy with a continuous workload at slower pace should be used

Test-Retest Reliability of a 4-Minute All-Out Critical Force Test in Rock Climbers

International Journal of Exercise Science 16(4): 912-923, 2023. The purpose of this study was to assess the test-retest reliability of a 4-minute all-out critical force test in well-trained rock climbers. Thirteen rock climbers (n=4 females) completed a familiarization session and two all-out critical force tests on different days. During each trial, participants completed 24 repetitions of 7s right-handed, maximal effort hangs from a 20mm edge interspersed with 3 s rest. The end-test force (EF; i.e., critical force), impulse above EF (IEF), and peak force achieved durin g the test were analyzed with paired t-tests to determine differences between trials. Intraclass correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman analysis were performed to quantify the relative and absolute reliability of the measure, respectively. The level of significance for this study was set at p\u3c0.05. There were no significant differences between trials for any of the reported variables (P≥0.455). For EF, IEF, and peak force, ICC was 0.848, 0.820, and 0.938, respectively; and CV was 21.0%, 13.2%, and 5.6%, respectively. Bland-Altman analyses showed a mean relative bias of -2.3%, -2.8%, and -1.3%, with 95% limits of agreement (LoA) of -62.6% to 58.1%, -40.5% to 30.9%, and -17.2% to 14.6% for EF, IEF, and peak force, respectively, however linear regression revealed a significant proportional bias for EF (p = 0.026, R2 = 0.377). The reliability of this protocol was good to excellent for all parameters; however, there was larger intra-individual variability for EF and IEF. This study suggests that when using the 4-min all-out critical force test in rock climbers, coaches and athletes should be aware that there may be a trade-off between the test’s practicality and the precision of its results

Electromyographic activity and applied load during high intensity elastic resistance and nautilus machine exercises

This study was designed to quantify and compare Electromyographic activity (EMG) and applied load in quadriceps muscle within performing high intensity knee extension exercises by Elastic Resistance (ER) and Nautilus Machine (NM). Sixteen male and female subjects (22.4 ± 4.7 yrs) completed 8 RM seated knee extension by NM, elastic tubing with original length (E0) and elastic tubing with 30 decrement of original length (E30). The mean value of EMG and external force were calculated and synchronized across various segments of motion for the three modes of training. The results demonstrated that in the early concentric and late eccentric segments of contraction, NM elicited significantly higher muscle activation than both E30 and E0 (p < 0.05). However, in the mid-concentric and mid-eccentric as well as late concentric and early eccentric segments no significant differences were observed between NM and E30. These findings supported the approach that developing external recoil of force in ER device by reducing 30 of initial length of elastic material can offer similar neuromuscular activation compared with NM. On this basis, E30 can be suggested as an affordable and non-gym based exercise device which has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of athletes. © Editorial Committee of Journal of Human Kinetics

Two practical strategies for developing resultant muscle torque production using elastic resistance device

This investigation was conducted to quantify and compare Resultant Muscle Torque (RMT) pattern in quadriceps muscle using elastic resistance training device. Sixteen subjects completed 8-RM seated knee extension by elastic tubing with original length (E0) and elastic tubing with 30 decrement of original length (E30). Every repetition was partitioned into 6 phases (3 concentric and 3 eccentric) and mean value for external force and acceleration were calculated and synchronized for every phase of lifting. The magnitude of Resultant Muscle Torque was calculated based on the equation recommended by Enoka (2002) for dynamic motions. the RMT values among various exercise types phases demonstrated significantly higher value for E30 compared with E0 (all P &lt; 0.05). This is except in the 3 rd and 4 th phases of contraction which no significant difference observed between E0 and E30. Accordingly, the magnitude of increasing RMT in phase 1 (2.6 ) and phase 6 (3.98 ) for E30 compared with E0 supported the effectiveness of two applied strategies in developing muscle torque production in ER exercises. © 2011 Springer-Verlag

Foam Rolling and Muscle and Joint Proprioception After Exercise-Induced Muscle Damage.

CONTEXT:Foam rolling (FR) is considered an effective postexercise modality for reducing delayed-onset muscle soreness and enhancing recovery of muscle function. However, the effects of FR on muscle and joint proprioception have not been investigated. OBJECTIVE:To examine the effects of FR on muscle and joint proprioception after an intense exercise protocol. DESIGN:Controlled laboratory study. SETTING:University-based laboratory. PATIENTS OR OTHER PARTICIPANTS:A total of 80 healthy, physically active male students were randomly assigned to either the FR (n = 40; age = 22.8 ± 3.3 years, height = 176.4 ± 5.3 cm, mass = 74.2 ± 6.4 kg) or passive-recovery (PR; n = 40; age = 23.0 ± 3.2 years, height = 178.1 ± 5.5 cm, mass = 74.6 ± 6.2 kg) group. INTERVENTION(S):Participants in both groups performed 4 sets of 25 repetitions of voluntary maximal eccentric contractions at 60°/s from 20° to 100° of knee flexion to induce exercise-induced muscle damage. The exercise was followed by either PR or 2 minutes of FR immediately (1 hour) and 24, 48, and 72 hours postexercise. MAIN OUTCOME MEASURE(S):Muscle soreness, pressure-pain threshold, quadriceps-muscle strength, joint position sense, isometric force sense, and threshold to detect passive movement at baseline and immediately, 24, 48, and 72 hours postexercise after FR. RESULTS:Foam rolling resulted in decreased muscle pain, increased pressure-pain threshold, improved joint position sense, attenuated force loss, and reduced threshold to detect passive movement compared with PR at 24 and 48 hours postexercise. CONCLUSIONS:Foam rolling postexercise diminished delayed-onset muscle soreness and improved recovery of muscle strength and joint proprioception. These results suggested that FR enhanced recovery from exercise-induced damage

Ubiquinol supplementation modulates energy metabolism and bone turnover during high intensity exercise

Pablo Mira-Rufino and Jorge Moreno-Fernandez are grateful to the Excellence Ph.D. Program "Nutricion y Ciencias de los Alimentos" from the University of Granada. Jorge Moreno-Fernandez was supported by the fellowship from the Ministry of Education, Culture and Sport (Spain). The authors thank the Fire Department of Granada for their participation in the current study.Bone and energy metabolism are profoundly influenced by exercise. The objective of this study was to determine for the first time whether a short-term supplementation with ubiquinol could have a modulating effect on bone turnover and energy metabolism associated with strenuous exercise. The participants (n= 100 healthy and well-trained firemen) were randomly divided into two groups: ubiquinol group (ubiquinol (200 mg day(-1))) and control group (placebo) for two weeks. The protocol consisted of conducting two identical strenuous exercise tests with a rest period between tests of 24 h. Blood samples were collected before supplementation (basal value) (T1), after supplementation (T2), after the first physical exercise test (T3), after 24 h of rest (T4), and after the second physical exercise test (T5). Parathyroid hormone (PTH), osteocalcin (OC), osteoprotegerin (OPG), osteopontin (OPN), sclerotin (SOST), alkaline phosphatase (AP), adrenocorticotropin (ACTH), insulin, leptin, adrenaline, noradrenaline and peroxisome proliferator activated receptor-gamma coactivator-1 alpha (PGC-1 alpha) were determined. Our protocol increased ACTH, SOST, PTH and OC levels, while it decreased OPN. This protocol also increased adrenaline, noradrenaline and PCG-1 alpha, and decreased insulin. After ubiquinol supplementation, PTH, OC, OPG, alkaline phosphatase, leptin, insulin, noradrenaline and PGC-1 alpha levels increased in the supplemented group compared to the control group after the exercise protocol. Strenuous exercise has a clear effect on energy metabolism and bone turnover. These effects are modulated by ubiquinol supplementation, which especially increases the biomarkers of bone formation during strenuous exercise. In addition, ubiquinol has a beneficial effect on the mobilization of energy sources, fact that it could represent an ergogenic and physiological advantage for skeletal muscles.Ministry of Education, Culture and Sport (Spain

Muscle pain induced by hypertonic saline in the knee extensors decreases single-limb isometric time to task failure

Purpose: Increased nociceptive activity and the experience of exercise-induced pain (EIP) may contribute to fatigue during endurance exercise. To investigate this, a pain model that produces pain similar to EIP and decouples its’ relationship to exercise intensity is required. This study 1) compared the quality of pain caused by a hypertonic saline injection into the vastus lateralis in resting and exercise conditions, and 2) investigated whether this pain contributes to changes in time to task failure. Methods: On separate days, eighteen participants completed a time to task failure at 20% maximal voluntary torque (MVT), a resting hypertonic saline intramuscular injection, and in a further three visits a time to task failure at 10% MVT following injection of isotonic saline, hypertonic saline or a control (no injection). Results: In a subset of eligible participants (n = 12), the hypertonic saline combined with 10% MVT produced a qualitative experience of pain (assessed by the McGill Pain Questionnaire) that felt similar to EIP. 10% MVT with hypertonic saline significantly elevated pain intensity in the first 20% of the time to task failure and caused a significantly (P < 0.05) shorter time to task failure (448 ± 240 s) compared with the isotonic saline (605 ± 285 s) and control (514 ± 197 s) conditions. Conclusion: These findings demonstrate that hypertonic saline increases the intensity of pain during exercise, which results in a faster occurrence of exercise-induced fatigue. These results provide important evidence supporting pain as a limiting factor in endurance performance

Muscle strength and damage following two modes of variable resistance training

Nautilus Machine (NM) and Elastic Resistance (ER) have gained considerable popularity among athletes and recreational lifters seeking to increase muscle strength. However, there is controversy concerning the use of ER for increasing muscle hypertrophy and strength among healthy-trained individuals. The aim of the study was to compare the effect of repeated near maximal contractions by ER/NM on indicators of muscle damage including: maximal strength decrement (MVIC), rate of muscle soreness (DOMS), concentration of plasma creatine kinase (CK) and increased high muscle signal on T2 weighted images using magnetic resonance imaging (MRI). Nine healthy male subjects completed two modalities of exercise (5 sets × 10RM ER/NM) in a counterbalance cross-over study design with three weeks “wash-out” period between experiments. The MVIC was measured and DOMS rated and recorded for 4 consecutive days while blood samples were collected on day 1, 3, 5 and 7. Prior to and forty eight hours after completion of each mode of exercise, subjects underwent MRI scanning. The average of applied forces demonstrated significantly higher value for NM compared with ER (362 ± 34.2 N vs 266.73 ± 44.6 N respectively) throughout the 5 sets of dynamic exercise (all p <0.05). However, the indicators of muscle damage (T2 relaxation time, DOMS, MVIC and serum CK) exhibited a very similar response across both modes of training. Plasma CK increased significantly following both modes of training with the peak value on Day 3 (p < 0.05). The time course of muscle soreness reached a significant level after both modes of exercise and showed a peak value on the 2nd day (p < 0.05). The T2 relaxation time demonstrated a statistically significant increase following ER and NM compared with the pre-test value (p < 0.05). The similarity of these responses following both the ER and NM exercise training session suggests that both modes of training provide a similar training stress; despite a considerably lower external force generation during ER. The importance of these findings is underlined by the fact that exercise-induced muscle damage has been shown to be the underlying mechanism of further muscle hypertrophy

Pain pressure threshold of a muscle tender spot increases following local and non-local rolling massage

Background The aim of the present study was to determine the acute effect of rolling massage on pressure pain threshold (PPT) in individuals with tender spots in their plantar flexor muscles. Methods In a randomized control trial and single blinded study, tender spots were identified in 150 participants’ plantar flexor muscles (gastrocnemius or soleus). Then participants were randomly assigned to one of five intervention groups (n = 30): 1) heavy rolling massage on the calf that exhibited the higher tenderness (Ipsi-R), 2) heavy rolling massage on the contralateral calf (Contra-R), 3) light stroking of the skin with roller massager on the calf that exhibited the higher tenderness (Sham), 4) manual massage on the calf that exhibited the higher tenderness (Ipsi-M) and 5) no intervention (Control). PPT was measured at 30 s and up to 15 min post-intervention via a pressure algometer. Results At 30 s post-intervention, the Ipsi-R (24 %) and Contra-R (21 %) demonstrated higher (p < 0.03) PPT values compared with Control and Sham. During 15 min post-intervention, PPT was higher (p < 0.05) following Ipsi-R (19.2 %), Contra-R (15.9 %) and Ipsi-M (10.9 %) compared with Control. There was no difference between the effects of three deep tissue massages (Ipsi-R, Ipsi-M and Contra-R) on PPT. Discussion Whereas the increased PPT following ipsilateral massage (Ipsi-R and Ipsi-M) might be attributed to the release of fibrous adhesions; the non-localized effect of rolling massage on the contralateral limb suggests that other mechanisms such as a central pain-modulatory system play a role in mediation of perceived pain following brief tissue massage. Conclusion Overall, rolling massage over a tender spot reduces pain perception. Trial registration ClinicalTrials.gov (NCT02528812), August 19th, 2015