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In the last 40 years, biomechanics has progressed significantly as a subdiscipline within kinesiology. The development of national and international societies dedicated to biomechanics and the increase in the number of scientific biomechanics journals has led to a growth in the biomechanics community. In the last few decades, the research focus in biomechanics has broadened substantially. With this diversity of focus, there have been many novel developments in new technologies used in biomechanics. Biomechanics has become an integral subdiscipline that has interfaced with several other areas in kinesiology and has contributed significantly to enhancing the knowledge base in all areas. Much of the development of biomechanics has resulted from improvements in the technology used in movement research. Although it may be overreaching to say that biomechanics can solve many human movement problems, the technology has allowed researchers to at least answer more comprehensive questions and answer them in greater depth.

Introduction: The elliptical trainer, developed to simulate running while minimizing joint loads, elicits a unique lower extremity biomechanical response. The purpose of this study was to examine the angular kinematics, peak net joint moments, and peak joint powers at the hip, knee and ankle joints while exercising at three different ramp settings on the elliptical trainer exercise machine (Precor EFX). Methods: Twenty-six healthy individuals with no history of lower extremity injury and with previous experience exercis- ing on an elliptical trainer volunteered for this study. Motion was captured with two cameras as subjects performed exer- cise at three ramp conditions. The pedal resistance was kept constant at the lowest setting. The pedals of the elliptical were fitted with three orthogonal load cells. Video and force data were synchronized and used to perform a 2D inverse dynamics analysis. Results: As the ramp inclination increased, subjects demonstrated greater amounts of ankle dorsiflexion, knee flexion, hip flexion and lesser degrees of plantar flexion and hip extension (p

Explosive resistance training (ERT) improves older adults' strength and power, and methods to make this form of training more accessible and useful to older adults are needed. The purpose of this study was to evaluate whether the rating of perceived exertion (RPE) scale would predict a broad range of ERT intensities on the leg press with older adults. If successful, then a load-RPE relationship could be used to regulate the intensity of training loads for ERT with older adults, allowing the elimination of maximal strength testing. Twenty-one older adults (≥65 years) with resistance training experience took part in 2 testing sessions. Session 1: Subjects performed high-velocity repetitions on the leg press for up to 9 loads (from 60 to 140% body weight) presented in quasi-randomized order, and then reported their RPE for each load. Session 2: A 1 repetition maximum (1RM) strength test was conducted. Regression analysis revealed that the average RPE across subjects for each load strongly predicted the average %1RM across subjects (R2 = 99.5%; p < 0.001). This allows the establishment of a load-RPE relationship for use in selecting ERT loads for older adults on the leg press. For example, high-intensity loads (70-90% 1RM) that would elicit both strength and power gains when used with ERT aligned with an RPE of 14-16. Lighter loads that may be useful for training for power, but not strength (

Mirrors are often used in an instructional environment where precise movements must be learned (e.g., martial arts, Pilates, dance). The potential for mirrors in the learning environment of a Pilates class, to affect the subsequent performance of a Pilates star movement when mirrors are not present, was examined. Twenty subjects learned the Pilates star movement over seven weeks, either with (n=11) or without (n=9), mirrors present in the Pilates studio. Performance of the star without mirrors present was assessed quantitatively before and after the training, by video analysis of the degree of lateral straightness of the subject's body at the start, middle, and end of the star movement. Performance of the star movement without a mirror present improved similarly for both the group that learned with, and the group that learned without, mirrors present (p

The present study examined the effect of a progressive, whole- body, high resistance training program on reported pain in older adults. Ninety-eight participants (60 - 83 years) completed the McGill Pain Questionnaire prior to and after an eight week training period. Seventy-nine of the participants completed a progressive, high resistance training program of 11 different exercises on three days a week. At the end of eight weeks, the training group achieved significant strength gains ranging from 62% -119% (p < 0.005). Pain measures for the training and control groups were compared using an analysis of covariance on post-test pain measures after an adjustment by pre-test scores. (p < 0.05). The training group reported less perceived pain than the control group in four pain measures (overall pain intensity, sensory dimension, miscellaneous pain measures, number of pain descriptors selected). There were no differences reported for the affective or evaluative dimensions of perceived pain, the number of painful areas, or the present pain. Results suggest that eight weeks of progressive, whole-body weight training has a positive impact on perception of pain in older adults

This study evaluated magnesium-creatine (MgCre) supplementation on body water and quadriceps torque. Maltodextran (Placebo), Mg oxide plus Cre (MgO-Cre), and Mg-creatine chelate (MgC-Cre) at 800 mg Mg and 5 g Cre per day were used for 2 weeks in 35 subjects in a random assignment, blinded study. Pre-post measures were completed with bioimpedance to determine total body water (TBW), extracellular water (ECF), and intracellular water (ICF), and an isokinetic device at 180 degrees per second for knee extension peak torque (T), total work (W), and power (PWR). Body weights increased for both treatment groups, MgO-Cre Delta 0.75 kg (P

A group of healthy older adults completed an 8-week resistance-training program. For 38 participants (14 men, 24 women; ages 60–90 years; M mass = 73.2 kg, SD = 12.3; M height = 1.65 m, SD = 0.08), pre- and postprogram sit-to-stand performance was analyzed (60 Hz video) focusing on center of mass kinematics surrounding transition. Significant changes were attributed to improved strength. Peak forward, downward, and upward velocities increased (16, 59, and 26%, respectively), and relative transition time was delayed 27%. These behaviors were more similar to those of healthy younger adults. Results also indicated strategy changes. Participants exploited their improved strength, forming a distinctive movement pattern emphasizing stability followed by a brisk rise. These adaptations represent meaningfully improved function in an important daily living activity.

This study examined the relationship between absolute and relative (1 repetition maximum/LBM) strength vs. 13 different functional measurements in 143 older adults (mean = 70.28, standard deviation = 7.90 years). Strength for 11 machine lifts was determined using a predicted 1-repetition maximal strength measurement. Zero-order correlation results between absolute and relative strength vs. function measures demonstrated very weak to moderate correlations in the range of 0.02-0.57 and 0.01-0.44, respectively, with the lowest correlations present between strength and balance measures and the highest correlations present between strength and the carrying task (p/= 0.05). Stepwise multiple regression results also confirmed the low predictability of functional tasks using strength measures, with absolute and relative strength measures accounting for only 3-38% and 3-33% of the various functional measures, respectively. This study identified specific strength measurements that contribute to the variance in a functional task but also clearly indicated that strength alone cannot serve as a predictor of function in older adults.

Soleus Hoffmann-reflex (H-reflex) modulation during walking was examined in 7 young and 13 elderly adults. H-reflex size was measured in 16 equal time divisions (phases) of the step cycle. In both the elderly and the young groups, the H reflex was minimal at the time of heel contact, rose to a maximum shortly after midstance, decreased rapidly as toe-off neared, then was minimal during swing. There was a significant interaction between age group and step cycle phase (p < .05). During midstance of walking, the elderly participants had a smaller H-reflex size during two of the 16 time phases of the step cycle (p < .05), despite no significant difference in H-reflex size between the age groups while standing. The smaller H-reflex size during the stance phase of walking may reflect changes in central reflex mechanisms that may impact stretch reflex contribution to ankle extensor neural drive and ankle stiffness in elderly persons during walking.

The aim of this study was to determine whether elderly and young adults with similar physical activity levels have similar soleus H-wave maximum/M-wave maximum ratios (H-reflex size) and to determine the relationship between H-reflex size and physical activity level. H-reflex size and physical activity levels were measured in 18 elderly (71 ± 5.7 years) and 20 young (24 ± 4.2) participants. The physical activity levels of the 2 groups were not significantly different. The elderly group had smaller H-rellexes than the young group (elderly. 36% ± 27%; young, 59% ± 17%; p < .05), but the effect of age on H-reflex size was only moderate (omega squared = .19, effect size = .30). There was a weak tendency for higher levels of physical activity to be associated with larger H reflexes (r = .38, p < .05). The findings indicate that soleus H-reflex size is not strongly associated with age or physical activity level.

The present study examined the effect of a progressive, whole- body, high resistance training program on reported pain in older adults. Ninety-eight participants (60 - 83 years) completed the McGill Pain Questionnaire prior to and after an eight week training period. Seventy-nine of the participants completed a progressive, high resistance training program of 11 different exercises on three days a week. At the end of eight weeks, the training group achieved significant strength gains ranging from 62% -119% (p ≤ 0.005). Pain measures for the training and control groups were compared using an analysis of covariance on post-test pain measures after an adjustment by pre-test scores. (p ≤ 0.05). The training group reported less perceived pain than the control group in four pain measures (overall pain intensity, sensory dimension, miscellaneous pain measures, number of pain descriptors selected). There were no differences reported for the affective or evaluative dimensions of perceived pain, the number of painful areas, or the present pain. Results suggest that eight weeks of progressive, whole-body weight training has a positive impact on perception of pain in older adults. Key pointsImproved strength in older adults had a positive effect on the perception of pain.The number of painful areas identified and self-reported pain qualities were diminished following high resistance weight training.The McGill Pain Questionnaire was an effective tool for measuring changes in pain perception as a result of training.

Soleus Hoffman-reflex (H-reflex) gain was compared at the same background level of electromyographic activity across lying, natural standing, and tandem stance postures, in 12 young and 16 elderly adults. When compared to a lying posture, young adults significantly depressed soleus H-reflex gain when in a natural standing (19% decrease) and a tandem stance position (30% decrease; p

The sprint starts of 12 skilled collegiate sprinter/hurdlers were filmed for four different sprint start conditions. Ground reaction forces were collected for the first step out of the blocks and velocities through a 2-m speed trap immediately following the first support phase were recorded. The subjects employed their preferred right-left leg placement in the blocks, while the anterior-posterior spacing of the front block with respect to the starting line and the amount of forward lean in the set position were varied. Four positions were constructed that accounted for anthropometric differences. The four positions consisted of combinations of two arm orientations (forward lean and perpendicular to ground) and two front block to starting line distances (bunched and elongated). Kinematic data were reduced to provide center of mass position and velocity measures and analyzed for critical periods throughout the starting action. Selected critical events from the first step kinetic records were also analyzed. The results indicated that the elongated starting positions resulted in greater horizontal displacement, greater propelling impulse, increased first step toe-off velocity, and greater average velocity through a 2-m speed trap. Arm orientation effects were less well defined. Forward lean tended to result in greater vertical velocity at block clearance and horizontal velocity at first step toe-off, whereas perpendicular arm positioning resulted in greater 2-m speed trap velocity.

This study examined the relationship between absolute and relative (1 repetition maximum/LBM) strength vs. 13 different functional measurements in 143 older adults (mean 5 70.28, standard deviation 5 7.90 years). Strength for 11 machine lifts was determined using a predicted 1-repetition maximal strength measurement. Zero-order correlation results between absolute and relative strength vs. function measures demonstrated very weak to moderate correlations in the range of 0.02‐0.57 and 0.01‐0.44, respectively, with the lowest correlations present between strength and balance measures and the highest correlations present between strength and the carrying task (p # 0.05). Stepwise multiple regression results also confirmed the low predictability of functional tasks using strength measures, with absolute and relative strength measures accounting for only 3‐38% and 3‐ 33% of the various functional measures, respectively. This study identified specific strength measurements that contribute to the variance in a functional task but also clearly indicated that strength alone cannot serve as a predictor of function in older adults.

PURPOSE This preliminary study attempted to identify the frequency of orthostatic hypotension (OH) in community dwelling older adults who volunteered to participate in an 8-week, heavy-resistance, strength-training program. It also assessed the effect of the strength-training program on OH. METHODS From a larger study (n = 53) on high-resistance strength training in older adults (mean age 71.4 +/- 6.6 years), a subset of subjects (n = 24), mean age 71.0 +/- 5.8 years, was evaluated who met at least one criterion for OH. All subjects were tested for resting blood pressures (BP) and heart rates (HR) in the supine, sitting, and standing positions. Also noted was their response to orthostatism in rising from a cot after 10 minutes and rising from a chair after 5 minutes. The subset was not different from the overall group in gender ratio, age, or effect of medication on BP. The treatment was an 8-week strength-training program at 80% of their one repetition maximum. RESULTS Significant changes (P < 0.05) were shown in supine diastolic BP (+3.2 mm Hg), sitting systolic BP (-3.9), and standing HR (+4.9 beats per minute). In response to the orthostatic challenge, significant (P < 0.05) improvements were shown in systolic BP (+9.7 mm Hg), diastolic BP (+4.7), and HR (+3.2 beats per minute) for the rise from chair, and in diastolic BP (+6.7 mm Hg) rise from the cot. CONCLUSIONS These data show that OH is not uncommon (45%) in community dwelling older adults. A strength training program in older adults has little effect on resting BP, but elicits a positive adaptation to an orthostatic challenge.

Ground-reaction force patterns were examined in three groups: sighted, blindfolded, and blind. Fifteen subjects, aged 19 to 41, participated in the study. Ten walking trials were collected over a 5-meter distance. The data were analyzed by normalization for body weight, extraction of specific ground-reaction force parameters through force-time curve analysis routines, and averaging across the ten trials for each subject. Results of a one-way analysis of variance indicated that there were no significant differences when force patterns were analyzed in terms of mediolateral and vertical ground-reaction force components. Blind subjects were shown to have significantly greater (p < 0.05) maximum braking and propelling forces.

The purpose of this study was to evaluate, using ground reaction force data, two ankle stabilizing techniques commonly used by athletic trainers; the closed Gibney taping procedure and the boot type ankle stabilizer. Each condition was examined in a pre- and postexercise bout. In addition, a no appliance condition was also tested. Eight healthy female athletes were required to perform ten satisfactory trials in each of the five conditions. Ten trial mean values of 34 descriptors of ground reaction force components for each subject/condition were evaluated using multivariate analyses of variance. No significant differences in any of the force or impulse variables were found across conditions. However, significant differences were found in three variables describing the relative timing of events in the footfall (p < 0.05). No significant differences were found between the pre- and postexercise conditions. The variability in the measured parameters. of the no appliance condition was consistently higher than the ankle appliance conditions. The implication of the study was that, in normal running, the ankle appliances did not appear to moderate or change foot function. J Orthop Sports Phys Ther 1986;7(5):244-249.

(1984). Ground Reaction Force Symmetry during Walking and Running. Research Quarterly for Exercise and Sport: Vol. 55, No. 3, pp. 289-293.

Tibial rotation and torque were evaluated using a specifically designed device to assess the effects of two different knee braces on the performance of the surgically repaired knee. Comparisons were also made with the healthy contralateral limb. Six subjects, aged 21 to 28, participated in the study. Subjects were tested while seated in an adjustable chair which allowed the torso, pelvis, thigh, and femoral condyles to be stabilized utilizing a series of straps and brackets. The foot was immobilized by a special boot which was connected to the input shaft of a Cybex isokinetic dynamometer. To begin, the foot was positioned perpendicular to the frontal plane and the knee position maintained at 90'' of flexion. Subjects were then asked to maximally externally or internally rotate the tibia on the femur during two brace conditions: the surgical limb condition and the healthy limb condition. The results indicated that there were differences across all conditions of tibia1 range of motion and torque with external direction values being significantly greater (P0.05). Comparison between conditions yielded no significant differences; however, a consistent trend characteristic of a knee brace reduction in internal rotation and torque parameters were present. J Orthop Sports Phys Ther 1984;6(2):116-122.

(1984). The Effects of Two- and Three-Day-Per-Week Aerobic Dance Programs on Maximal Oxygen Uptake. Research Quarterly for Exercise and Sport: Vol. 55, No. 2, pp. 172-174.

The influence of knee bracing was evaluated during the activity of running by examining ground reaction forces and knee joint movement parameters assessed electrogoniometrically. Twenty-one subjects were assigned to 1 of 3 groups based on medical records provided by a physician: normal or non-injury group; anterior cruciate ligament lesion/laxity group; and anterior cruciate ligament repair group. Four test conditions were investigated: healthy or control limb; injured or experimental limb; Generation II knee brace; and Marquette Knee Stabilizer knee brace. Ten running trials were performed for each condition at a photoelectrically controlled running pace (3.33 +/- 0.11 m X s-1). There were no significant differences as a result of group membership for both electrogoniometer and force platform analyses (P less than 0.05). There was a significant difference across the four test conditions. Both knee brace applications were shown to significantly reduce knee flexion during swing and support, total rotation, and total varus/valgus movement parameters of the experimental knee joint. Both brace applications were also shown to alter the experimental limb by increasing the relative time to the achievement of the initial collision force, creating a greater collision force and thereby creating larger impulses in both the vertical and foreaft directions during the initial contact phase.