Rate of force development and rapid muscle activation characteristics of knee extensors in very old men

Introduction: The primary aims of the present study were to assess the relationships of early (0–50 ms) and late (100–200 ms) knee extensor rate of force development (RFD) with maximal voluntary force (MVF) and sit-to-stand (STS) performance in participants with chronic kidney disease (CKD) not requiring dialysis.Methods: Thirteen men with CKD (eGFR = 35.17 ±.5 ml/min per 1.73 m2, age = 70.56 ±.4 years) and 12 non-CKD men (REF) (eGFR = 80.31 ± 4.8 ml/min per 1.73 m2, age = 70.22 ±.9 years) performed maximal voluntary isometric contractions to determine MVF and RFD of the knee extensors. RFD was measured at time intervals 0–50 ms (RFD0−50) and 100–200 ms (RFD100−200). STS was measured as the time to complete five repetitions. Measures of rectus femoris grayscale (RF GSL) and muscle thickness (RF MT) were obtained via ultrasonography in the CKD group only. Standardized mean differences (SMD) were used to examine differences between groups. Bivariate relationships were assessed by Pearson's product moment correlation.Results: Knee extensor MVF adjusted for body weight (CKD=17.14 ±.1 N·kg0.67, REF=21.55 ±.3 N·kg0.67, SMD = 0.79) and STS time (CKD = 15.93 ±.4 s, REF = 12.23 ±.7 s, SMD = 1.03) were lower in the CKD group than the REF group. Absolute RFD100−200 was significantly directly related to adjusted MVF in CKD (r = 0.56, p = 0.049) and REF (r = 0.70, p = 0.012), respectively. STS time was significantly inversely related to absolute (r = −0.75, p = 0.008) and relative RFD0−50 (r = −0.65, p = 0.030) in CKD but not REF (r = 0.08, p = 0.797; r = 0.004, p = 0.991). Significant inverse relationships between RF GSL adjusted for adipose tissue thickness and absolute RFD100−200 (r =−0.59, p = 0.042) in CKD were observed.Conclusion: The results of the current study highlight the declines in strength and physical function that occur in older men with CKD stages 3b and 4 not requiring dialysis. Moreover, early RFD was associated with STS time in CKD while late RFD was associated MVF in both CKD and REF.Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT03160326 and NCT02277236.

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Aging, muscle fiber type, and contractile function in sprint-trained athletes

Journal of Applied Physiology ◽

10.1152/japplphysiol.00299.2006 ◽

2006 ◽

Vol 101 (3) ◽

pp. 906-917 ◽

Cited By ~ 161

Author(s):

Marko T. Korhonen ◽

Alexander Cristea ◽

Markku Alén ◽

Keijo Häkkinen ◽

Sarianna Sipilä ◽

...

Keyword(s):

Fiber Type ◽

Cross Sectional Area ◽

Rate Of Force Development ◽

Knee Extensors ◽

Type I ◽

Sectional Area ◽

Cross Sectional ◽

Specific Tension ◽

Force Development ◽

Aging Muscle

Biopsy samples were taken from the vastus lateralis of 18- to 84-yr-old male sprinters ( n = 91). Fiber-type distribution, cross-sectional area, and myosin heavy chain (MHC) isoform content were identified using ATPase histochemistry and SDS-PAGE. Specific tension and maximum shortening velocity ( Vo) were determined in 144 single skinned fibers from younger (18–33 yr, n = 8) and older (53–77 yr, n = 9) runners. Force-time characteristics of the knee extensors were determined by using isometric contraction. The cross-sectional area of type I fibers was unchanged with age, whereas that of type II fibers was reduced ( P < 0.001). With age there was an increased MHC I ( P < 0.01) and reduced MHC IIx isoform content ( P < 0.05) but no differences in MHC IIa. Specific tension of type I and IIa MHC fibers did not differ between younger and older subjects. Vo of fibers expressing type I MHC was lower ( P < 0.05) in older than in younger subjects, but there was no difference in Vo of type IIa MHC fibers. An aging-related decline of maximal isometric force ( P < 0.001) and normalized rate of force development ( P < 0.05) of knee extensors was observed. Normalized rate of force development was positively associated with MHC II ( P < 0.05). The sprint-trained athletes experienced the typical aging-related reduction in the size of fast fibers, a shift toward a slower MHC isoform profile, and a lower Vo of type I MHC fibers, which played a role in the decline in explosive force production. However, the muscle characteristics were preserved at a high level in the oldest runners, underlining the favorable impact of sprint exercise on aging muscle.

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Evaluation of Strength and Muscle Activation Indicators in Sticking Point Region of National-Level Paralympic Powerlifting Athletes

Journal of Functional Morphology and Kinesiology ◽

10.3390/jfmk6020043 ◽

2021 ◽

Vol 6 (2) ◽

pp. 43

Author(s):

Felipe J. Aidar ◽

Filipe Manuel Clemente ◽

Dihogo Gama de Matos ◽

Anderson Carlos Marçal ◽

Raphael Fabrício de Souza ◽

...

Keyword(s):

Muscle Activation ◽

Isometric Force ◽

National Level ◽

Rate Of Force Development ◽

Static Test ◽

Force Development ◽

Intermediate Phases ◽

Maximum Isometric Force ◽

Dynamic Time ◽

Sticking Point

Background: The sticking region is considered an intervening factor in the performance of the bench press with high loads. Objective: To evaluate the strength indicators in the sticking point region in Powerlifting Paralympic athletes. Methods: Twelve Brazilian Powerlifting Paralympic athletes performed maximum isometric force (MIF), rate of force development (RFD), time at MIF, velocity, dynamic time in sticking, and surface electromyography in several distances from the bar to the chest. Results: For velocity, there was a difference between the pre-sticking and sticking region (1.98 ± 0.32 and 1.30 ± 0.43, p = 0.039) and dynamic time between the pre-sticking and the sticking region (0.40 ± 0.16 and 0.97 ± 0.37, p = 00.021). In static test for the MIF, differences were found between 5.0 cm and 15.0 cm (CI 95% 784; 1088; p = 0.010) and between 10.0 cm and 5.0 cm (CI 95% 527; 768; p < 0.001). Regarding the RFD, differences were found (CI 95% 938; 1240; p = 0.004) between 5.0 cm and 25.0 cm and between 10.0 cm and 25.0 cm (CI 95% 513; 732; p < 0.001). In relation to time, there were differences between 5.0 cm and 15.0 cm (CI 95% 0.330; 0.515; p < 0.001), 5.0 cm, and 25.0 cm (CI 95% 0.928; 1.345; p = 0.001), 10.0 cm and 15.0 cm (p < 0.05) and 15.0 cm and 25.0 cm (p < 0.05). No significant differences were observed between the muscles in electromyography, although the triceps showed the highest muscle activation values. Conclusions: The maximum isometric force, rate of force development, time, velocity, and dynamic time had lower values, especially in the initial and intermediate phases in the sticking region.

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

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.654443 ◽

2021 ◽

Vol 15 ◽

Author(s):

Darjan Smajla ◽

Jure Žitnik ◽

Nejc Šarabon

Keyword(s):

Outcome Measure ◽

Isometric Force ◽

Cross Sectional Study ◽

Scaling Factor ◽

Rate Of Force Development ◽

Knee Extensors ◽

Cross Sectional ◽

Force Development ◽

Wide Range ◽

Neuromuscular Assessment

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 (kRFD–SF) and RFR-SF slope (kRFR–SF) calculation, (2) to introduce a new outcome measure – theoretical peak of rate of force development/relaxation (TPRFD and TPRFR) and (3) to investigate differences and associations between kRFD–SF and kRFR–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 kRFD–SF and kRFR–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 kRFD–SF and kRFR–SF. We confirmed the negligibility of the y-intercepts and confirmed the reliability of the newly introduced TPRFD and TPRFR. Large negative associations were found between kRFD–SF and kRFR–SF (r = 0.502, p < 0.001), while comparison of the absolute values showed a significantly higher kRFD–SF (8.86 ± 1.0/s) compared to kRFR–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 TPRFD and TPRFR 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.

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Validation of jump squats as a practical measure of post-activation potentiation

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0277 ◽

2013 ◽

Vol 38 (3) ◽

pp. 306-313 ◽

Cited By ~ 6

Author(s):

Maria L. Nibali ◽

Dale W. Chapman ◽

Robert A. Robergs ◽

Eric J. Drinkwater

Keyword(s):

Latin Square ◽

Conditioning Stimulus ◽

Rate Of Force Development ◽

Knee Extensors ◽

Sports Performance ◽

Mean Power ◽

Muscle Twitch ◽

Training Environment ◽

Force Development ◽

Practical Measure

To determine if post-activation potentiation (PAP) can augment sports performance, it is pertinent that researchers be confident that any enhancement in performance is attributable to the PAP phenomenon. However, obtaining mechanistic measures of PAP in the daily training environment of highly trained athletes is impractical. We sought to validate jump squats as a practical measure with ecological validity to sports performance against a mechanistic measure of PAP. We assessed the evoked muscle twitch properties of the knee extensors and jump squat kinetics of 8 physically trained males in response to a 5-repetition-maximum back squat conditioning stimulus (CS). Evoked muscle twitch, followed by 3 jump squats, was assessed before and at 4, 8, and 12 min post CS. Time intervals were assessed on separate occasions using a Latin square design. Linear regression was used to determine the relationship between post–pre changes in kinetic variables and muscle twitch peak force (Ft) and twitch rate of force development (RFDt). Large correlations were observed for both concentric relative and absolute mean power and Ft (r = 0.50 ± 0.30) and RFDt (r = 0.56 ± 0.27 and r = 0.58 ± 0.26). Concentric rate of force development (RFD) showed moderate correlations with Ft (r = 0.45 ± 0.33) and RFDt (r = 0.49 ± 0.32). Small-to-moderate correlations were observed for a number of kinetic variables (r = −0.42–0.43 ± 0.32–0.38). Jump squat concentric mean power and RFD are valid ecological measures of muscle potentiation, capable of detecting changes in athletic performance in response to the PAP phenomenon.

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Training-induced changes in muscle CSA, muscle strength, EMG, and rate of force development in elderly subjects after long-term unilateral disuse

Journal of Applied Physiology ◽

10.1152/japplphysiol.01307.2003 ◽

2004 ◽

Vol 97 (5) ◽

pp. 1954-1961 ◽

Cited By ~ 172

Author(s):

Charlotte Suetta ◽

Per Aagaard ◽

Anna Rosted ◽

Ane K. Jakobsen ◽

Benn Duus ◽

...

Keyword(s):

Muscle Strength ◽

Strength Training ◽

Muscle Mass ◽

Muscle Activation ◽

Muscle Force ◽

Rate Of Force Development ◽

Muscle Size ◽

Elderly Subjects ◽

Force Development

The ability to develop muscle force rapidly may be a very important factor to prevent a fall and to perform other tasks of daily life. However, information is still lacking on the range of training-induced neuromuscular adaptations in elderly humans recovering from a period of disuse. Therefore, the present study examined the effect of three types of training regimes after unilateral prolonged disuse and subsequent hip-replacement surgery on maximal muscle strength, rapid muscle force [rate of force development (RFD)], muscle activation, and muscle size. Thirty-six subjects (60–86 yr) were randomized to a 12-wk rehabilitation program consisting of either 1) strength training (3 times/wk for 12 wk), 2) electrical muscle stimulation (1 h/day for 12 wk), or 3) standard rehabilitation (1 h/day for 12 wk). The nonoperated side did not receive any intervention and thereby served as a within-subject control. Thirty subjects completed the trial. In the strength-training group, significant increases were observed in maximal isometric muscle strength (24%, P < 0.01), contractile RFD (26–45%, P < 0.05), and contractile impulse (27–32%, P < 0.05). No significant changes were seen in the two other training groups or in the nontrained legs of all three groups. Mean electromyogram signal amplitude of vastus lateralis was larger in the strength-training than in the standard-rehabilitation group at 5 and 12 wk ( P < 0.05). In contrast to traditional physiotherapy and electrical stimulation, strength training increased muscle mass, maximal isometric strength, RFD, and muscle activation in elderly men and women recovering from long-term muscle disuse and subsequent hip surgery. The improvement in both muscle mass and neural function is likely to have important functional implications for elderly individuals.

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Rate of force development and muscle activation of trunk muscles in women with and without low back pain: A case-control study

Physical Therapy in Sport ◽

10.1016/j.ptsp.2016.12.007 ◽

2017 ◽

Vol 26 ◽

pp. 41-48 ◽

Cited By ~ 3

Author(s):

Denise Martineli Rossi ◽

Mary Hellen Morcelli ◽

Adalgiso Coscrato Cardozo ◽

Benedito Sérgio Denadai ◽

Mauro Gonçalves ◽

...

Keyword(s):

Low Back Pain ◽

Back Pain ◽

Muscle Activation ◽

Case Control Study ◽

Case Control ◽

Rate Of Force Development ◽

Trunk Muscles ◽

Low Back ◽

Force Development ◽

Control Study

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The effects of hypohydration and fatigue on neuromuscular activation performance

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0189 ◽

2013 ◽

Vol 38 (1) ◽

pp. 21-26 ◽

Cited By ~ 13

Author(s):

Claire Minshull ◽

Lewis James

Keyword(s):

Body Mass ◽

Repeated Measures ◽

Joint Angle ◽

Peak Force ◽

Rate Of Force Development ◽

Knee Extensors ◽

Fluid Restriction ◽

Joint Stability ◽

Force Development ◽

Neuromuscular Performance

This study investigated the effects of hypohydration by fluid restriction on voluntary and evoked indices of neuromuscular performance at a functional joint angle. Measures of static volitional peak force (2–3–s maximal muscle actions) and evoked peak twitch force, electromechanical delay, and rate of force development were obtained from the knee extensors (30° knee flexion) of 10 males (age, 24 (4) years; height, 1.76 (0.10) m; body mass, 78.7 (9.13) kg (mean (SD))) prior to and immediately following 24 h of (i) euhydration (EU) and (ii) hypohydration (HYP). Neuromuscular performance was also assessed in response to a fatiguing task (3 × 30-s maximal static knee extensions) following each condition. Repeated-measures ANOVAs showed that HYP was associated with a significant 2.1% loss in body mass (p < 0.001) and a 7.8% reduction in volitional peak force (p < 0.05). Following fatigue, data indicated statistically similar levels of impairment to volitional peak force (11.6%, p < 0.01) and rate of force development (21.0%, p < 0.01) between conditions (EU; HYP). No changes to any other indices of performance were observed. The substantive hypohydration-induced deficits to muscle strength at this functional joint angle might convey a decreased performance capability and should be considered by the hypohydrated athlete. Whilst hypohydration did not affect fatigue-related performance of the knee extensors, the additive changes associated with lower baseline levels of strength performance (7.8%) and fatigue (11.6%) coupled with slower rate of muscle force production (from 0–100 ms) following fatigue may present significant challenges to the maintenance of dynamic knee joint stability, particularly at this vulnerable joint position.

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