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Bryce Dyer, Siamak Noroozi, Philip Sewell and Sabi Redwood

The purpose of this paper is to investigate the role of lower-limb running prostheses and stakeholders’ perceptions of fairness in relation to their use in competitive disability sport. A Delphi study was conducted over three rounds to solicit expert opinion in a developing area of knowledge. High levels of consensus were obtained. The findings suggest that the prosthesis is defined as a piece of sporting equipment to restore athletes’ function to enable them to take part in disability sport. In addition, the panel determined that the development of this technology should be considered to be integral to the sport’s ethos. Crucially, prostheses technology should be monitored and have limits placed upon it to ensure fairness for both participants and stakeholders.

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Viviane Ribeiro de Ávila, Teresa Bento, Wellington Gomes, José Leitão and Nelson Fortuna de Sousa

Context Ankle fractures (AFs) are the most common injuries among the fractures of the lower limbs found in urgency and emergency services. 1 , 2 These fractures are a significant source of morbidity for both the young and elderly population. 3 , 4 At a young age, the incidence is higher in men

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David Diggin, Ross Anderson and Andrew J. Harrison

Evidence suggests reports describing the reliability of leg-spring (kleg) and joint stiffness (kjoint) measures are contaminated by artifacts originating from digital filtering procedures. In addition, the intraday reliability of kleg and kjoint requires investigation. This study examined the effects of experimental procedures on the inter- and intraday reliability of kleg and kjoint. Thirty-two participants completed 2 trials of single-legged hopping at 1.5, 2.2, and 3.0 Hz at the same time of day across 3 days. On the final test day a fourth experimental bout took place 6 hours before or after participants’ typical testing time. Kinematic and kinetic data were collected throughout. Stiffness was calculated using models of kleg and kjoint. Classifications of measurement agreement were established using thresholds for absolute and relative reliability statistics. Results illustrated that kleg and kankle exhibited strong agreement. In contrast, kknee and khip demonstrated weak-to-moderate consistency. Results suggest limits in kjoint reliability persist despite employment of appropriate filtering procedures. Furthermore, diurnal fluctuations in lower-limb muscle-tendon stiffness exhibit little effect on intraday reliability. The present findings support the existence of kleg as an attractor state during hopping, achieved through fluctuations in kjoint variables. Limits to kjoint reliability appear to represent biological function rather than measurement artifact.

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Cindy Y. Lin, Liang-Ching Tsai, Joel Press, Yupeng Ren, Sun G. Chung and Li-Qun Zhang

Context:

Gluteal-muscle strength has been identified as an important component of injury prevention and rehabilitation in several common knee injuries. However, many conventionally prescribed gluteal-strengthening exercises are not performed during dynamic weight-bearing activities, which is when most injuries occur.

Objectives:

To compare lower-limb muscle-activation patterns between conventional gluteal-strengthening exercises and off-axis elliptical exercises with motorized foot-plate perturbations designed to activate gluteal muscles during dynamic exercise.

Evidence Acquisition:

Twelve healthy volunteers (26.1 ± 4.7 y) participated in the study. They performed 3 conventional exercises (single-leg squat, forward lunge, and clamshell) and 3 elliptical exercises (regular, while resisting an adduction force, and while resisting an internal-rotation torque). Gluteus medius (GMed) and maximus (GMax), quadriceps, hamstrings, and gastrocnemius muscle activations during each exercise were recorded using surface electromyography (EMG) and normalized to maximal voluntary isometric contraction (MVIC).

Evidence Synthesis:

Normalized GMed EMG was the highest during the adduction-resistance elliptical exercise (22.4% ± 14.8% MVIC), significantly greater than forward lunge (8.2% ± 3.8% MVIC) and regular elliptical (6.4% ± 2.5% MVIC) and similar to clamshell (19.1% ± 8.8% MVIC) and single-leg squat (18.4% ± 7.9% MVIC). Normalized GMax EMG during adduction-resistance (11.1% ± 7.6% MVIC) and internal-rotation-resistance elliptical (7.4% ± 3.8% MVIC) was significantly greater than regular elliptical (4.4% ± 2.4% MVIC) and was similar to conventional exercises. The single-leg squat required more muscle activation from the quadriceps and gastrocnemius than the elliptical exercises.

Conclusions:

Off-axis elliptical exercise while resisting an adduction force or internal-rotation torque activates gluteal muscles dynamically while avoiding excessive quadriceps activation during a functional weight-bearing activity compared with conventional gluteal-strengthening exercises.

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Antoine Falisse, Sam Van Rossom, Johannes Gijsbers, Frans Steenbrink, Ben J.H. van Basten, Ilse Jonkers, Antonie J. van den Bogert and Friedl De Groote

backgrounds. Its standard workflow is offline, although an OpenSim-based real-time system was recently developed to compute inverse kinematics and inverse dynamics for lower-limb applications. 30 Finally, Human Body Model does not require user inputs to create a model and is therefore robust against user

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Ryan G. Timmins, Baubak Shamim, Paul J. Tofari, Jack T. Hickey and Donny M. Camera

groups) would promote a lengthening of BFlh fascicle length with reductions in pennation angle and improvements in lower limb strength. Whereas, it was hypothesized that the END stimulus would result in a shortening of BFlh fascicles, increases in pennation angle, and no changes in lower limb strength

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Luiz Henrique Palucci Vieira, Felipe de Souza Serenza, Vitor Luiz de Andrade, Lucas de Paula Oliveira, Fábio Pamplona Mariano, Juliana Exel Santana and Paulo Roberto Pereira Santiago

The aims of the current study were to analyze a kick from 10 m in a futsal context and the parameters of muscular strength using an isokinetic dynamometer in a laboratory environment, performed with the dominant (DL) and nondominant lower limbs (NDL). Seventeen professional elite players participated. Kicking performance was evaluated from the second penalty mark. Next, athletes completed a strength evaluation with an isokinetic dynamometer at speeds of 60°⋅s–1, 180°⋅s–1, and 300°⋅s–1. Significant differences were observed for hip (15.64 ± 3.44; 13.97 ± 2.62), ankle (63.19 ± 8.90; 52.55 ± 8.72), foot (82.31 ± 7.93; 68.41 ± 7.85), and ball (99.74 ± 8.45; 88.31 ± 7.93) speeds (km⋅h–1), and average power at 180°⋅s–1 (325.59 ± 40.47; 315.79 ± 39.49 W), but not for accuracy (1.33 ± 0.57; 1.66 ± 0.77 m) between the DL and NDL, respectively. Few moderate correlations were observed in the DL (r = .54–.64) or NDL (r = .53–.55) between the kinematic variables of kick and muscular strength parameters (P < .05). We conclude that highly trained players present asymmetries in kicking motion; however, the imbalance in muscular strength is very small. We recommend that specific court tests be conducted to reliably characterize kicking performance in futsal. Success in kicking seems to be too variable and complex to be totally predicted only by joints, foot and ball speed, and lower limb muscular strength parameters.

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Jeroen Vrints, Erwin Koninckx, Marc Van Leemputte and Ilse Jonkers

Saddle position affects mechanical variables during submaximal cycling, but little is known about its effect on mechanical performance during maximal cycling. Therefore, this study relates saddle position to experimentally obtained maximal power output and theoretically calculated moment generating capacity of hip, knee and ankle muscles during isokinetic cycling. Ten subjects performed maximal cycling efforts (5 s at 100 rpm) at different saddle positions varying ± 2 cm around the in literature suggested optimal saddle position (109% of inner leg length), during which crank torque and maximal power output were determined. In a subgroup of 5 subjects, lower limb kinematics were additionally recorded during submaximal cycling at the different saddle positions. A decrease in maximal power output was found for lower saddle positions. Recorded changes in knee kinematics resulted in a decrease in moment generating capacity of biceps femoris, rectus femoris and vastus intermedius at the knee. No differences in muscle moment generating capacity were found at hip and ankle. Based on these results we conclude that lower saddle positions are less optimal to generate maximal power output, as it mainly affects knee joint kinematics, compromising mechanical performance of major muscle groups acting at the knee.

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Dagny Bengs, Ira Jeglinsky, Jukka Surakka, Thomas Hellsten, Joachim Ring and Jyrki Kettunen

Context: Using technical clothes with electrodes embedded in the clothing makes it possible to record the electrical activity produced by the activity of the skeletal muscles in activities of daily living. Objective: To investigate the reliability of measuring lower-limb left-right electromyography (EMG) activity ratio with smart shorts during stair descent, stair ascent, and repeated unloaded squats among healthy working-aged subjects. Methods: Seventeen females (mean age 25.5 y), and 17 males (mean age 29.9 y) participated in this test-retest protocol carried out twice on the same day. Results: Intraclass correlation coefficient (ICC) varied from .65 to .80 in the different activities. Mean difference and limits of agreement (LOA) between the repeated measurements were for descending stairs –0.8%, LOA –6.2% to 4.7%; for ascending stairs –0.9%, –6.5% to 4.7%; and for squats –0.2%, –5.4% to 4.9%. The coefficient of repeatability for descending stairs was 5.6%, for ascending stairs 5.7%, and for squats 5.3%. Conclusions: Our study among healthy subjects showed that the left-right EMG activity ratio in activities of daily living can be reliably measured with smart shorts. In future research, the feasibility of technical clothes as a follow-up method in rehabilitation should be investigated in greater detail.

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Tanya Trayers, Debbie A. Lawlor, Kenneth R. Fox, Jo Coulson, Mark Davis, Afroditi Stathi and Tim Peters

Associations of objectively measured physical activity (PA) with objectively measured lower limb function in adults age 70 and older were studied. Lower limb function was assessed using the Short Physical Performance Battery (SPPB) and PA by an accelerometer providing mean daily counts per minute (CPM), mean daily steps and minutes of moderate or vigorous PA (MVPA) per day. A minority (32 [13%]) scored low (≤6 out of a maximum of 12) on the SPPB, but only 3 (1%) achieved recommended PA levels. Adjusting for confounders, the odds ratio of low SPPB (≤6) comparing those in the lowest one third to highest two thirds of mean CPM was 55 (95%CI: 6, 520); for mean steps per day it was 23 (95%CI: 4, 137) and for minutes of MVPA per day 56 (95%CI: 6, 530). Low levels of PA are common and are associated with poor levels of lower limb function in older adults.