Dataset Information

Effect of position and alteration in synergist muscle force contribution on hip forces when performing hip strengthening exercises.

ABSTRACT:

Background

Understanding the magnitude and direction of joint forces generated by hip strengthening exercises is essential for appropriate prescription and modification of these exercises. The purpose of this study was to evaluate hip joint forces created across a range of hip flexion and extension angles during two hip strengthening exercises: prone hip extension and supine hip flexion.

Methods

A musculoskeletal model was used to estimate hip joint forces during simulated prone hip extension and supine hip flexion under a control condition and two altered synergist muscle force conditions. Decreased strength or activation of specific muscle groups was simulated by decreasing the modeled maximum force values by 50%. For prone hip extension, the gluteal muscle strength was decreased in one condition and the hamstring muscle strength in the second condition. For supine hip flexion, the strength of the iliacus and psoas muscles was decreased in one condition, and the rectus femoris, tensor fascia lata, and sartorius muscles in the second condition.

Findings

The hip joint forces were affected by hip joint position and partially by alterations in muscle force contribution. For prone hip extension, the highest net resultant force occurred with the hip in extension and the gluteal muscles weakened. For supine hip flexion, the highest resultant forces occurred with the hip in extension and the iliacus and psoas muscles weakened.

Interpretation

Clinicians can use this information to select exercises to provide appropriate prescription and pathology-specific modification of exercise.

SUBMITTER: Lewis CL

PROVIDER: S-EPMC2677193 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Publications

Effect of position and alteration in synergist muscle force contribution on hip forces when performing hip strengthening exercises.

Lewis Cara L CL Sahrmann Shirley A SA Moran Daniel W DW

Clinical biomechanics (Bristol, Avon) 20081122 1

<h4>Background</h4>Understanding the magnitude and direction of joint forces generated by hip strengthening exercises is essential for appropriate prescription and modification of these exercises. The purpose of this study was to evaluate hip joint forces created across a range of hip flexion and extension angles during two hip strengthening exercises: prone hip extension and supine hip flexion.<h4>Methods</h4>A musculoskeletal model was used to estimate hip joint forces during simulated prone h ...[more]

PMID: 19028000

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Project description:A further increase in the number of total hip arthroplasty (THA) is predicted, in particular the number of young THA patients has raised and with it their demands. There is no standardized evidence-based rehabilitation program and no reliable guidelines for sports activities after THA. Stretching and strengthening gymnastics are routinely performed in rehabilitation and aerobics as a sport after THA. The aim of the investigation was to determine the in vivo force and moments acting on the hip prosthesis during gymnastics and aerobic exercises to provide a source for evidence-based recommendations. Hip joint loads were measured in six patients with instrumented hip implants. The resulting force FRes, bending moment MBend at the neck and torsional moment MTors at the stem were examined during seven strengthening (with two different resistance bands) and four stretching gymnastic exercises and seven aerobic exercises with and without an aerobic step board compared to the loads during the reference activity walking. The stretching and strengthening gymnastics exercises and the aerobic exercises with and without a board demonstrated in their median peak force and moments mostly lower or similar values compared to walking. Significantly increased loads were recorded for the flexor stretching exercise in monopod stand (Fres and MBend), the strengthening abduction exercise on the chair (MTors) and the strengthening flexion exercise with the stronger resistance band (MTors). We also found a significant increase in median peak values in aerobic exercises with a board for the "Basic Step" (ipsilateral started Fres and MTors; contralateral started MTors), "Kickstep ipsilateral started" (Fres and MTors) and "Over the Top contralateral started" (Fres). The in vivo loads in THA patients during frequently performed stretching, strengthening and aerobic exercises were demonstrated for the first time. It was proved that stretching gymnastic exercises are safe in terms of resulting force, bending and torque moments for THA patients, although an external assistance for stabilization may be considered. Strengthening gymnastics exercises are reliable in terms of Fres, MBend and MTors, but, based on our data, we recommend to adhere to the communicated specific postoperative restrictions and select the resistance bands with lower tension. Aerobic exercises without an aerobic board can be considered as reliable activity in terms of force and moments for THA patients. Aerobic exercises with a board are not recommended for the early postoperative period and in our opinion need to be adapted to the individual muscular and coordinative resources.

Project description:Integrated exercises that mimic daily tasks are generally preferred for improving performance and the later stages of rehabilitation, but it is unknown whether integrated core exercises are better than isolated core exercises at improving muscle activation for hypertrophy. The aim of the study was to compare the electromyographic (EMG) activity in rectus abdominis, oblique externus, and erector spinae while performing three conditions of integrated core exercises (lunges) with three isolated core exercises (prone bridge, side bridge and back extension). The three conditions of lunges were: on a stable surface, unstable surface and with external resistance to the trunk using an elastic band. The external resistance was measured with a force cell and peaked at 75N. After one familiarization session, all exercises were performed in one experimental session in randomized order. The isolated core exercises were performed in 20 seconds and the time performing the five repetitions with lunges was matched (20 seconds). Significantly greater peak normalized EMG activity were observed in the isolated core exercises compared to the three integrated core exercises (P<0.001) with two exceptions. For the oblique externus, the isolated core exercise was only greater than the stable lunge. Lunges with elastic bands only demonstrated greater peak erector spinae activation compared the other lunge conditions. Comparing the mean EMG activity between the isolated and three integrated exercises, greater muscle activations were observed performing the isolated exercises (P<0.001). Unstable lunges did not increase the peak or mean core muscle activations. In conclusion, mean and peak EMG activity performing the isolated exercises were in general greater than the three condition of lunges. Based on these results, we recommend using isolated core exercises when the primary goal is to improve muscle activation and elicit hypertrophy, but integrated exercises once adequate initial hypertrophy is achieved.

Dataset Information

Effect of position and alteration in synergist muscle force contribution on hip forces when performing hip strengthening exercises.

Background

Methods

Findings

Interpretation

Publications

Effect of position and alteration in synergist muscle force contribution on hip forces when performing hip strengthening exercises.

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