Biomedical subjects

John H Hollman

Publications and source records attributed to John H Hollman.

13 recordsLinked to original sources

PubMed2007

Influence of lever arm and stabilization on measures of hip abduction and adduction torque obtained by hand-held dynamometry.

OBJECTIVE: To examine the reliability of clinical techniques for testing hip abductor and adductor muscle performance. DESIGN: Repeated measures. SETTING: Academic laboratory. PARTICIPANTS: A sample of 21 healthy subjects (12 men, 9 women) between 22 and 31 years of age. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Reliability of repeated measures was estimated by calculating intraclass correlation coefficients. Torque production capability was calculated by multiplying force output obtained with a hand-held dynamometer by the length of the resistance lever arm. RESULTS: The reliability of abduction testing was greatest in the long-lever condition. Adduction test reliability was greatest in the long-lever condition with bench stabilization. The maximal hip abduction torque tested in the long-lever position was significantly greater (t(20)=9.21, P<.001) than that in the short-lever position. The maximal hip adduction torque occurred using a long lever for resistance application and a bench to stabilize the nontest leg (F(1,20)=15.64, P=.001). CONCLUSIONS: Muscle performance testing of hip abductors and adductors with a hand-held dynamometer can be performed with good to excellent intratester and intertester reliability. Hip abduction testing is best performed with a long lever. Hip adduction is best performed with a long lever and a bench to stabilize the nontest extremity.

Adult↗

PubMed2006

Does walking in a virtual environment induce unstable gait? An examination of vertical ground reaction forces.

Virtual reality (VR) can induce postural instability in standing and walking, as quantified with kinematic parameters. This study examines the effect of a VR environment on kinetic gait parameters. Ten healthy volunteers walked on an instrumented treadmill in a VR environment and a non-VR environment. In the VR environment, a corridor with colored vertical stripes comprising the walls was projected onto a concave screen placed in front of the treadmill. The speed of the moving image was perceptually equivalent to the speed of the treadmill, creating an illusion that subjects walked through the corridor. Vertical ground reaction forces were sampled. Kinetic parameters that reflect gait stability (weight acceptance peak force, weight acceptance rate, push-off peak force and push-off rate) were compared between the VR and non-VR environments. Subjects walked in the VR environment with increased magnitudes and rates of weight acceptance force and with increased rates of push-off force. Variability in weight acceptance rates and peak forces, and variability in push-off peak forces, were also increased in the VR environment. The gait deviations reflect a compensatory response to visual stimulation that occurs in the VR environment, suggesting that walking in a VR environment may induce gait instability in healthy subjects.

Adult↗

PubMed2006

Age-related differences in spatiotemporal markers of gait stability during dual task walking.

Increased stride-to-stride variability during walking characterizes gait instability and predicts falling in older adults. Walking while performing cognitive tasks (dual task walking) is also associated with increased risk of falling. The purpose of the study was to examine whether gait velocity and stride-to-stride variability in gait velocity differ in older adults compared with middle-aged and younger adults during normal and dual task walking conditions. Sixty older (n=20, mean age=81 years), middle-aged (n=20, mean age=48 years), and young adults (n=20, mean age=25 years) participated in the study. Gait parameters were quantified with GAITRite instrumentation. In the dual task condition, participants spelled five-letter words in reverse while walking across the walkway. Across groups, gait velocity was slower (p<0.001) and stride-to-stride variability in gait velocity was greater (p=0.001) in dual task walking. Older subjects walked more slowly than did middle-aged and younger subjects and the difference in gait velocity was greatest in the dual task condition (p<0.05). Variability in stride velocity was increased in older subjects compared with middle-aged and younger subjects (p<0.05). Additionally, in older subjects, impaired walking performance was associated with impaired cognitive performance in dual task walking. The gait changes observed in dual task walking characterize decreased gait stability and indicate that cognitively demanding tasks during walking have a destabilizing effect on gait and may place older people at a greater risk of falling.

Adult↗

PubMed2006

Agreement between the GAITRite walkway system and a stopwatch-footfall count method for measurement of temporal and spatial gait parameters.

OBJECTIVE: To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the stopwatch-footfall count technique. DESIGN: Criterion standard. SETTING: Research laboratory in a physical therapy education program. PARTICIPANTS: Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. INTERVENTIONS: Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. MAIN OUTCOME MEASURES: Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the stopwatch-footfall count technique. RESULTS: Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and -.05m/s for walking speed, between -1.5 and -24.3 steps/min for cadence, and between .01 and .37m for stride length. CONCLUSIONS: This study shows that the GAITRite and stopwatch-footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the stopwatch-footfall count technique.

Adult↗

PubMed2006

The effects of gender, age, and body mass index on standing lumbar curvature in persons without current low back pain.

Reference values for standing lumbar curvature (SLC) obtained via noninvasive methods are not well established in persons without current low back pain. The effect of gender is considered to have a significant effect on SLC with women having more lumbar lordosis than men. The effect of age and degree of obesity are not considered to have a statistically significant effect on SLC. The purpose of this study was to test the assumption that measurements of SLC in healthy adults obtained by a flexible curve will differ between genders, whereas the SLC will not differ across categories of age and body mass index (BMI). Two hundred thirty-five volunteers (119 men and 116 women) whose ages ranged between 20 and 79 years participated in the study. Subjects were almost exclusively White and from the Midwest. Measurements of the SLC were obtained by a flexible curve. The curve's shape was transferred to poster board, and the value of SLC was quantified by a previously described technique. A three-way analysis of variance (alpha = 0.05) was used to examine the main effects of gender, age, and BMI on SLC. The effect of gender (F1,199 = 21.4, p < 0.0001) and the effect of age (F5,199 = 2.8, p < 0.017) were statistically significant. The effect of BMI (F2,199 = 1.8, p = 0.176) was not significant. Women (mean, 49.5 degrees +/-10.7 degrees ) demonstrated about 6.5 degrees more SLC than their male (mean, 43.0 degrees +/-10.7 degrees ) counterparts. For age, the only significant difference was between the 20 to 29- and 50 to 59-year-old age categories. This study provides physical therapists with typical values of SLC in men and women without current low back pain.

Adult↗

PubMed2006

The contribution of golf to daily physical activity recommendations: how many steps does it take to complete a round of golf?

To quantify the number of steps adults take during an 18-hole round of golf, we recruited 42 healthy volunteers (12 men and 30 women aged 30-80 years) with established United States Golf Association handicaps to complete an 18-hole round of golf on each of 3 municipal golf courses. Subjects walked each course while wearing a pedometer to record step data. Analysis revealed that each golfer took a mean +/- SD 11,948 +/- 1781 steps per 18-hole round of golf. Regardless of handicap level, sex, or course played, most subjects exceeded 10,000 steps during a typical round of golf. Consequently, in most cases, walking 18 holes of golf will meet the recommendation to accumulate 10,000 steps per day as part of a general physical activity plan.

Activities of Daily Living↗

PubMed2005

Spatiotemporal gait deviations in a virtual reality environment.

Previous research suggests that postural sway in standing increases in virtual reality (VR) environments. This study was conducted to examine whether gait instability is prevalent when people walk in a VR environment. Ten healthy adults participated in the study. Subjects walked on a treadmill in a VR environment and a non-VR environment at each of three walking speeds: 0.9, 1.1, and 1.3 m/s. In the VR environment, an endless corridor with colored vertical stripes comprising the walls was projected onto a hemispherical screen placed in front of the treadmill. The speed of the moving corridor image was matched to the speed of the treadmill to create the illusion that subjects were walking through the endless corridor. Spatiotemporal data during gait were collected with an instrumented treadmill housing two piezoelectric force platforms. Gait parameters reflective of gait instability (stride length, step width, variability in stride velocity, and variability in step width) were compared between the VR and non-VR environments. Subjects walked in the VR environment with reduced stride lengths (p = 0.001), increased step widths (p = 0.001), and with increased variability in stride velocity (p < 0.001) and step width (p = 0.002). The gait deviations suggest that walking in a VR environment may induce gait instability in healthy subjects.

Adult↗

PubMed2005

Abdominal muscle performance as measured by the double leg-lowering test.

OBJECTIVE: To describe abdominal muscle performance as measured by the double leg-lowering test (DLLT) in healthy subjects. DESIGN: Repeated measures. SETTING: Academic laboratory. PARTICIPANTS: A sample of 100 healthy volunteers (50 men, 50 women; age range, 18-29 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Repeat measurements of the DLLT to determine reliability and performance standards and to identify variables that predict performance. RESULTS: The intraclass correlation coefficient (ICC 3,1) for repeated measures of the DLLT was .98. The mean value +/- standard error of the mean for abdominal performance for men was 15.4 degrees +/-2.3 degrees from a horizontal reference, and for women it was 36.9 degrees +/-3.4 degrees . A significant difference was found between men and women on performance of the DLLT (t 98 = -5.3, P < .001). A linear regression model found sex (t = -3.2, P = .002) and age (t = -4.6, P < .001) to be significant predictors of performance on the DLLT. CONCLUSIONS: The DLLT has excellent intratester reliability. We also found a sex difference in the performance of the DLLT.

Abdominal Muscles↗

PubMed2005

Comparison of muscle activation using various hand positions during the push-up exercise.

Popular fitness literature suggests that varied hand placements during push-ups may isolate different muscles. Scientific literature, however, offers scant evidence that varied hand placements elicit different muscle responses. This study examined whether different levels of electromyographic (EMG) activity in the pectoralis major and triceps brachii muscles are required to perform push-ups from each of 3 different hand positions: shoulder width base, wide base, and narrow base hand placements. Forty subjects, 11 men and 29 women, performed 1 repetition of each push-up. The EMG activity for subjects' dominant arm pectoralis major and triceps brachii was recorded using surface electrodes. The EMG activity was greater in both muscle groups during push-ups performed from the narrow base hand position compared with the wide base position (p < 0.05). This study suggests that, if a goal is to induce greater muscle activation during exercise, then push-ups should be performed with hands in a narrow base position compared with a wide base position.

Adult↗

PubMed2005

The influence of gender and age on hamstring muscle length in healthy adults.

STUDY DESIGN: Cross-sectional descriptive study. OBJECTIVES: To examine the factors of gender and age, stratified by 10-year increments, on hamstring muscle length (HML) as measured by passive straight-leg raise (PSLR) and popliteal angle (PA). BACKGROUND: Differences in HML between men and women have not been examined for a large group of healthy adults over a wide range of ages. The usefulness of these data is to provide some typical values of HML for future reference. METHODS AND MEASURES: Two hundred fourteen adults (108 women, 106 men; age range, 20-79 years) with no known history of hip or knee joint disease and no history of recent hamstring strain participated in the study. PSLR (trunk-thigh angle) and PA (thigh-leg angle) were estimated with a goniometer. A 2-way analysis of variance (ANOVA) was used to analyze the effects of 2 independent variables (gender and age) on 2 dependent variables (PSLR and PA). Statistical significance was established at alpha<.05. RESULTS: HML differed significantly (P<.001) between genders for both methods of measurement, with females demonstrating greater flexibility than their male counterparts. The difference between genders was 8 degrees for PSLR and 11 degrees for PA. HML was not influenced by age. CONCLUSIONS: This study provides physical therapists with typical values of HML in healthy men and women.

Adult↗

PubMed2003

Spasticity, strength, and gait changes after surgery for cervical spondylotic myelopathy: a case report.

STUDY DESIGN: A case report with repeated measures is presented. OBJECTIVE: To describe an objective method for evaluating changes in upper- and lower-extremity spasticity and strength, as well as temporal and kinematic gait variables, after surgical intervention for cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Degenerative cervical spinal disease is a common disorder, with some form of spondylosis demonstrated radiographically in more than 80% of those older than 55 years. Normative pre- and postoperative objective data quantifying spasticity, strength, and gait do not exist. METHODS: A 65-year-old woman underwent C2-C3 anterior cervical discectomy and fusion for progressive myelopathy secondary to a spondylosis and disc herniation. The measure for spasticity and strength at the ankles and elbows and a gait analysis were collected before surgery and at 11 days, 3 and 6 months after surgery. Spasticity and strength were assessed using a dynamometer, and a six-camera video system was used to record the gait. RESULTS: Preoperative left elbow flexor spasticity was more than 10 times greater than the values for the able bodies. It was reduced to normal levels after surgery. Substantial presurgery weakness was present in the elbow flexors and extensors bilaterally. Elbow extensor strength was at able-body levels after surgery. Gait speed was 57% of the able-body level before surgery and 78% of the able-body level 6 months after surgery. CONCLUSIONS: This case study demonstrated the role of biomechanics in characterizing impairments associated with cervical spondylosis and its surgical intervention. Measures for spasticity, strength, and gait taken before and after surgery indicated a favorable outcome. This report provides a foundation for the continued use of biomechanical methods to measure changes in function and impairments associated with surgical intervention of cervical spine disorders.

Aged↗

PubMed2003

Gender differences in surface rolling and gliding kinematics of the knee.

The purpose of the current study was to determine whether knee surface rolling and gliding kinematics differed between genders during open and closed kinetic chain movement conditions. Eleven unimpaired adults (six men and five women) participated in this study. Sagittal plane path of instant center of rotation measurements were obtained with videographic motion analysis and applied to a mathematical knee model from which joint surface rolling and gliding kinematics were obtained. In addition, normalized electromyographic data were collected from subjects' quadriceps and hamstring muscles. During closed kinetic chain knee extension, as the knee approached terminal extension, female participants showed significantly greater relative joint surface gliding than male participants. Female participants also extended the knee in the closed kinetic chain with less relative hamstring activity than males. The relationship between joint surface gliding and relative hamstring activity in females during closed kinetic chain knee extension may explain, in part, the greater incidence of noncontact anterior cruciate ligament injury that occurs in females.

Adult↗

PubMed2002

Knee joint movements in subjects without knee pathology and subjects with injured anterior cruciate ligaments.

BACKGROUND AND PURPOSE: Although weight-bearing (WB) exercise and increased hamstring muscle activity may contribute to knee joint stability in knees with an injured anterior cruciate ligament (ACL), the relationship among ACL integrity, muscle activity, and joint surface motion is not fully understood. The purpose of this study was to investigate whether knee joint rolling and gliding movements and electromyographic (EMG) activity differed between subjects with injured ACLs and subjects without knee pathology. SUBJECTS: Fifteen subjects with injured ACLs (9 men and 6 women; mean age=26 years, SD=7, range=18-36) and 15 age- and sex-matched subjects without knee pathology (9 men and 6 women; mean age=25 years, SD=6, range=18-36) participated in the study. METHODS: Sagittal-plane knee joint rolling and gliding movements and lower-extremity EMG activity were measured during non-weight-bearing (NWB) and WB movements. Mixed-model analyses of variance were conducted to analyze rolling and gliding and EMG data. RESULTS: During NWB knee extension, greater joint surface gliding occurred in knees with injured ACLs at full knee extension. During WB knee extension, greater gliding occurred in knees with injured ACLs throughout the range of motion tested. No differences in EMG activity occurred between groups. DISCUSSION AND CONCLUSION: The results suggest that, in the absence of increased hamstring muscle activity, anterior tibial displacement is not reduced in knees with injured ACLs during WB movement.

Adult↗