Ergogenic and Physiological Outcomes Derived From a Novel Skin Cooling Device.

ABSTRACT: Gray, WD, Jett, DM, Cocco, AR, Vanhoover, AC, Colborn, CE, Pantalos, GM, Stumbo, J, Quesada, PM, and Caruso, JF. Ergogenic and physiological outcomes derived from a novel skin cooling device. J Strength Cond Res 35(2): 391-403, 2021-Our study's purpose assessed a cooling headband's ergogenic and physiological impacts. Subjects (15 women and 13 men) completed six visits; the final 3 entailed rowing workouts with the following treatment conditions: no head cooling (NoHC), intermittent head cooling during exercise (HCex), and intermittent head cooling during exercise and post-exercise recovery (HCex&post). Data collection occurred at the following times (a) pre-exercise and post-warm-up, (b) between stages of up to eight 2-minute bouts, and (c) at 5, 10, 15, and 20 minutes post-exercise. In addition to distance rowed, thermal, cardiovascular, perceptual, and metabolic measurements were obtained. Results included a small yet significant intertreatment difference (HCex, HCex&post > NoHC) for distance rowed. Our cardiovascular and metabolic indices exhibited sex and time differences but likely did not contribute to the ergogenic effect. Yet, left hand temperatures (LHT) exhibited significant 2-way and 3-way interactions that were the likely source of the ergogenic effect. Auditory canal temperature (AUDT) results suggest the head is sensitive to heat increases, yet LHT data show headband use evoked significantly greater temperature increases at the hand's palmar surface, indicative of heat transfer. We conclude, and our practical applications suggest, the headband's ergogenic effect was manifested by cold-induced vasodilation at the hand's palmar surface, rather than heat losses through the head.

Biomechanics of Lower Limbs during Walking among Candidates for Total Knee Arthroplasty with and without Low Back Pain.

The effect of joint pathologies, such as unilateral knee osteoarthritis (UKOA) or low back pain (LBP), on bilateral gait symmetry has gained increased attention during the past decade. This study is the first to compare gait patterns between patients with UKOA and LBP in combination and with UKOA only. Temporal, kinematic, and kinetic variables were measured bilaterally during gait stance phase in 31 subjects with UKOA and LBP (Group I) and 11 subjects with only UKOA (Group II). Group I patients exhibited less hip rotation in the affected limb (A) than in the nonaffected (NA) limb during walking in contrast to Group II patients. Group I patients had minimal bilateral differences in hip abduction and flexion, but Group II patients displayed significantly larger values in the NA limb compared to the A limb for both parameters. Hip flexion patterns were significantly different between Groups I and II. Subjects in both groups adapted gait patterns that minimized vertical ground reaction force, knee flexion motion, and stance time on the UKOA affected limb. The distinct kinematic gait patterns that were revealed in this study may provide clinical value for assessment of patients with UKOA in conjunction with LBP.

A musculoskeletal modeling approach for estimating anterior cruciate ligament strains and knee anterior-posterior shear forces in stop-jumps performed by young recreational female athletes.

The central goal of this study was to contribute to the advancements being made in determining the underlying causes of anterior cruciate ligament (ACL) injuries. ACL injuries are frequently incurred by recreational and professional young female athletes during non-contact impact activities in sports like volleyball and basketball. This musculoskeletal-neuromuscular study investigated stop-jumps and factors related to ACL injury like knee valgus and internal-external moment loads, knee anterior-posterior (AP) shear forces, ACL strains and internal forces. Motion capture data was obtained from the landing phase of stop-jumps performed by eleven young recreational female athletes and electromyography (EMG) data collected from quadriceps, hamstring and gastrocnimius muscles which were then compared to numerically estimated activations. Numerical simulation tools used were Inverse Kinematics, Computed Muscle Control and Forward Dynamics and the knee modeled as a six degree of freedom joint. Results showed averaged peak strains of 12.2 ± 4.1% in the right and 11.9 ± 3.0% in the left ACL. Averaged peak knee AP shear forces were 482.3 ± 65.7 N for the right and 430.0 ± 52.4 N for the left knees, approximately equal to 0.7-0.8 times body weight across both knees. A lack of symmetry was observed between the knees for valgus angles (p < 0.04), valgus moments (p < 0.001) and muscle activations (p < 0.001), all of which can be detrimental to ACL stability during impact activities. Comparisons between recorded EMG data and estimated muscle activations show the relation between electrical signal and muscle depolarization. In summary, this study outlines a musculoskeletal simulation approach that provides numerical estimations for a number of variables associated with ACL injuries in female athletes performing stop-jumps.

A retrospective study of the relationship between back pain and unilateral knee osteoarthritis in candidates for total knee arthroplasty.

The purpose of this study was to determine the presence and temporal relationship between back pain and knee osteoarthritis (OA). All subjects were candidates for unilateral total knee arthroplasty (TKA) to relieve knee pain related to OA, and information regarding the prevalence of back pain was collected via questionnaires. A total of 42 subjects with unilateral knee OA responded to the questionnaires, and 74% of subjects reported chronic back pain, which first occurred approximately 10 years before their becoming candidates for TKA. All but 1 subject reported the onset of back pain prior to TKA candidacy, and less than 15% of subjects felt that their worst back pain occurred after the onset of knee OA. The results of this study are a first step toward quantifying the temporal relationship between back pain and unilateral knee OA, and future studies will look to assess potential risk factors for knee OA such as strength, biomechanical, and anatomical asymmetry.

A numerical simulation approach to studying anterior cruciate ligament strains and internal forces among young recreational women performing valgus inducing stop-jump activities.

Anterior cruciate ligament (ACL) injuries are commonly incurred by recreational and professional women athletes during non-contact jumping maneuvers in sports like basketball and volleyball, where incidences of ACL injury is more frequent to females compared to males. What remains a numerical challenge is in vivo calculation of ACL strain and internal force. This study investigated effects of increasing stop-jump height on neuromuscular and bio-mechanical properties of knee and ACL, when performed by young female recreational athletes. The underlying hypothesis is increasing stop-jump (platform) height increases knee valgus angles and external moments which also increases ACL strain and internal force. Using numerical analysis tools comprised of Inverse Kinematics, Computed Muscle Control and Forward Dynamics, a novel approach is presented for computing ACL strain and internal force based on (1) knee joint kinematics and (2) optimization of muscle activation, with ACL insertion into musculoskeletal model. Results showed increases in knee valgus external moments and angles with increasing stop-jump height. Increase in stop-jump height from 30 to 50 cm lead to increase in average peak valgus external moment from 40.5 ± 3.2 to 43.2 ± 3.7 Nm which was co-incidental with increase in average peak ACL strain, from 9.3 ± 3.1 to 13.7 ± 1.1%, and average peak ACL internal force, from 1056.1 ± 71.4 to 1165.4 ± 123.8 N for the right side with comparable increases in the left. In effect this study demonstrates a technique for estimating dynamic changes to knee and ACL variables by conducting musculoskeletal simulation on motion analysis data, collected from actual stop-jump tasks performed by young recreational women athletes.

Symmetry of ground reaction forces and muscle activity in asymptomatic subjects during walking, sit-to-stand, and stand-to-sit tasks.

In addition to walking, essential activities of daily living include the ability to rise from a seated position and sit from a standing position. Although many high-quality studies have been performed on these common functional tasks, the objective of the current research is to quantify symmetry indices (SI) of ground reaction force (GRF) and electromyographical (EMG) variables between the non-dominant (ND) and dominant (D) sides of the body in asymptomatic subjects during walking, sit-to-stand, and stand-to-sit tasks. Thirty-five healthy subjects consented to participate in the study that included collection of bilateral GRF and muscle activity of the back, trunk, and legs during the stance phase of walking and sit-stand tasks. No significant differences in SI values between the ND and D sides of the body were found, indicating that asymptomatic subjects walk, stand up, and sit down in a rather symmetric manner. Gait stance time, peak vertical GRF at heel strike, and peak vertical GRF during the entire sit-stand cycle were found to be "perfectly symmetrical" with SI values equal to 1. Future studies will involve similar analyses to determine the level of asymmetry among symptomatic subjects.

Prehabilitation before total knee arthroplasty increases strength and function in older adults with severe osteoarthritis.

Preparing for the stress of total knee arthroplasty (TKA) surgery by exercise training (prehabilitation) may improve strength and function before surgery and, if effective, has the potential to contribute to postoperative recovery. Subjects with severe osteoarthritis (OA), pain intractable to medicine and scheduled for TKA were randomized into a usual care (UC) group (n = 36) or usual care and exercise (UC + EX) group (n = 35). The UC group maintained normal daily activities before their TKA. The UC + EX group performed a comprehensive prehabilitation program that included resistance training using bands, flexibility, and step training at least 3 times per week for 4-8 weeks before their TKA in addition to UC. Leg strength (isokinetic peak torque for knee extension and flexion) and ability to perform functional tasks (6-minute walk, 30 second sit-to-stand repetitions, and the time to ascend and descend 2 flights of stairs) were assessed before randomization at baseline (T1) and 1 week before the subject's TKA (T2). Repeated-measures analysis of variance indicated a significant group by time interaction (p < 0.05) for the 30-second sit-to-stand repetitions, time to ascend the first flight of stairs, and peak torque for knee extension in the surgical knee. Prehabilitation increased leg strength and the ability to perform functional tasks for UC + EX when compared to UC before TKA. Short term (4-8 weeks) of prehabilitation was effective for increasing strength and function for individuals with severe OA. The program studied is easily transferred to a home environment, and clinicians working with this population should consider prehabilitation before TKA.

Prehabilitation versus usual care before total knee arthroplasty: A case report comparing outcomes within the same individual.

This case report compared pre- and postoperative functional ability, knee strength, and pain of a female who underwent two separate total knee arthroplasty (TKA) procedures. The female patient was part of a larger research study. The first surgery on the right knee was preceded with usual care and the second surgery on the left knee was preceded by prehabilitation. Functional ability was assessed by a 6-minute walk, chair raises, and the time required to ascend and descend stairs. Knee extension and flexion isokinetic strength was assessed using the KinCom Isokinetic Dynamometer. Pain was assessed using the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC). Functional abilities, knee strength, and pain were assessed at baseline measurements 4 weeks before surgery, 1 week before surgery, and at 1 and 3 months post surgery during each TKA procedure. Results indicate that the prehabilitation intervention had a favorable impact on improving functional ability up to 30%, increasing knee strength by 50% and decreasing pain prior to the left knee TKA. For this patient, prehabilitation increased functional ability and strength prior to surgery. Gains in strength were maintained in the nonsurgical knee after surgery. These findings indicate that prehabilitation may be effective at facilitating the rehabilitation following a TKA.

The effect of prehabilitation exercise on strength and functioning after total knee arthroplasty.

OBJECTIVE: The purpose of this study was to examine the effect of a preoperative exercise intervention on knee pain, functional ability, and quadriceps strength among patients with knee osteoarthritis before and after total knee arthroplasty (TKA) surgery. DESIGN: A repeated-measures design was used to compare 2 groups over 4 data collection points. SETTING AND PATIENTS: Community-dwelling subjects with osteoarthritis of the knee who were scheduled for a unilateral TKA were recruited from a single orthopedic surgeon's office and were randomized into control (n = 28) or prehab groups (n = 26). INTERVENTIONS: The control patients maintained usual care before their TKA. The exercisers performed prehabilitation exercises, which included resistance training, flexibility, and step training, 3 times per week before their TKA. OUTCOME MEASURES: Knee pain, functional ability, quadriceps strength, and strength asymmetry were assessed at baseline (T1), at 1 week before the patients' TKA (T2), and again at 1 (T3) and 3 (T4) months after TKA. RESULTS: The exercisers improved their sit-to-stand performance at T2, whereas the control group did not change their performance of functional tasks and had increased pain at T2. At T3 the exercisers demonstrated improved sit-to-stand performance. The control patients at T3 exhibited decreases in pain, their 6-minute walk, surgical leg strength and an increase in their nonsurgical leg strength and leg strength asymmetry. At T4 the exercisers improved in their performance of 3 of the 4 functional tasks, decreased all of their pain measures, and increased their surgical and nonsurgical quadriceps strength. At T4 the control group improved their performance on 2 of the 4 functional tasks, decreased all of their pain measures, increased their nonsurgical leg strength, and exhibited greater leg strength asymmetry. CONCLUSION: These findings appear to indicate the efficacy of prehabilitation among TKA patients and support the theory of prehabilitation.

Swimming as a model of task-specific locomotor retraining after spinal cord injury in the rat.

BACKGROUND: The authors have shown that rats can be retrained to swim after a moderately severe thoracic spinal cord contusion. They also found that improvements in body position and hindlimb activity occurred rapidly over the first 2 weeks of training, reaching a plateau by week 4. Overground walking was not influenced by swim training, suggesting that swimming may be a task-specific model of locomotor retraining. OBJECTIVE: To provide a quantitative description of hindlimb movements of uninjured adult rats during swimming, and then after injury and retraining. METHODS: The authors used a novel and streamlined kinematic assessment of swimming in which each limb is described in 2 dimensions, as 3 segments and 2 angles. RESULTS: The kinematics of uninjured rats do not change over 4 weeks of daily swimming, suggesting that acclimatization does not involve refinements in hindlimb movement. After spinal cord injury, retraining involved increases in hindlimb excursion and improved limb position, but the velocity of the movements remained slow. CONCLUSION: These data suggest that the activity pattern of swimming is hardwired in the rat spinal cord. After spinal cord injury, repetition is sufficient to bring about significant improvements in the pattern of hindlimb movement but does not improve the forces generated, leaving the animals with persistent deficits. These data support the concept that force (load) and pattern generation (recruitment) are independent and may have to be managed together with respect to postinjury rehabilitation.

Predictors of functional task performance among patients scheduled for total knee arthroplasty.

Osteoarthritis (OA) is a common health problem affecting more than 7 million Americans. Declines in strength, flexibility, and knee joint pain reduce functional ability and contribute to decisions for total knee arthroplasty (TKA). This study describes predictors of functional ability among knee patients scheduled for TKA and proposes a preoperative exercise program to improve functional ability. A total of 82 knee OA patients (average age = 62.7 +/- 7.48 years, 70% women) were recruited from a single orthopedic surgeon's office. Muscular fitness assessments included knee flexion, extension strength, and range of motion (ROM) of the surgical and nonsurgical knees. Functional ability was assessed by 6-minute walk, number of chair rises in 30 seconds, and time required to ascend and descend 2 flights of stairs. Perceived functional ability and pain were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index. Correlation matrices determined which measures of muscular fitness, pain, and perceptions were associated with measures of functional ability. Significant correlates were entered into regression equations that determined the significant predictors of the functional tasks. These regression equations identified flexion strength of the nonsurgical knee as predicting 24-45% of the variance of functional ability assessments that involved independent or consecutive knee movement. Other variables that, to a lesser degree, predicted performance of the functional ability assessments included knee joint ROM and body mass index. Because functional ability after TKA is strongly dependent on presurgical functional ability, future investigators may wish to examine the impact of improving presurgical functional ability of TKA patients through resistance training, particularly closed-kinetic chain exercises that transfer fewer forces through the knee joint.

Prehabilitation before knee arthroplasty increases postsurgical function: a case study.

Conditioning the body to undergo physical stress such as joint arthroplasty has been termed prehabilitation. This case study examined the effect of a 4-week prehabilitation intervention on functional outcomes after total knee arthroplasty (TKA). Two female subjects completed baseline strength and functional assessments before TKA. Subjects were randomized to either a 4-week prehabilitation intervention (ES) aimed at increasing strength and range of motion or a usual care condition (CS). After 4 weeks of training, subjects were reassessed and underwent TKA. Subjects completed a final assessment 12 weeks after TKA. Functional outcomes included 6-minute walk, number of times up from a chair in 30 seconds, proprioception, and self-reported function and pain using the Western Ontario and McMaster Universities Osteoarthritis Index. The data suggest that 4 weeks of prehabilitation had a positive effect on functional task performance and knee proprioception before surgery. After surgery, the ES continued to exhibit higher levels of functioning and less pain compared with the CS. Prehabilitation before TKA may contribute to improved recovery after surgery.

A two-input sliding-mode controller for a planar arm actuated by four pneumatic muscle groups.

Multiple-input sliding-mode techniques are applied to a planar arm actuated by four groups of pneumatic muscle (PM) actuators in opposing pair configuration. The control objective is end-effector tracking of a desired path in Cartesian space. The inputs to the system are commanded input pressure differentials for the two opposing PM groups. An existing model for the muscle is incorporated into the arm equations of motion to arrive at a two-input, two-output nonlinear model of the planar arm that is affine in the input and, therefore, suitable for sliding-mode techniques. Relationships between static input pressures are derived for suitable arm behavior in the absence of a control signal. Simulation studies are reported.

The effects of cycling shoe stiffness on forefoot pressure.

Plantar pressure data were recorded in two different shoe types to determine the effect of cycling shoe stiffness on peak plantar forefoot pressure in cyclists. Two pairs of shoes of the same size and manufacturer, identical except for outsole material and stiffness, were tested. Shoe stiffness measurements were collected under controlled conditions and in two different configurations using a dynamic hydraulic tensile testing machine. Measurements of plantar pressure were done using Pedar capacitive-based sensor insoles while subjects pedaled in a seated position at a controlled power output. Power output was set at a constant value of 400 W across all subjects by a magnetic resistance trainer unit. The pressure distribution in carbon-fiber-composite shoes during cycling was compared to cycling shoes made with plastic soles. Carbon fiber shoes presented stiffness values 42% and 550% higher than plastic shoes in longitudinal bending and three-point bending, respectively. The shoes made with carbon fiber produced peak plantar pressures 18% higher than those of plastic design (121 kPa vs. 103 kPa, p = .005). Competitive or professional cyclists suffering from metatarsalgia or ischemia should be especially careful when using carbon fiber cycling shoes because the shoes increase peak plantar pressure, which may aggravate these foot conditions.

The use of end-to-side nerve grafts to reinnervate the paralyzed orbicularis oculi muscle.

Facial paralysis is a serious neurologic disorder, particularly when it affects the eye. Loss of the protective blink reflex may lead to corneal ulceration and, possibly, visual loss. The purpose of this study was to compare different nerve-grafting techniques to reanimate the paralyzed eyelid. Sixteen adult dogs (25 kg each) were allocated into four groups. Denervation of the left hemi-face was performed in all cases. One dog served as a control animal (group I). Group II dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group III dogs (n = 5) underwent end-to-end coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group IV dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact and denervated palpebral branches. The animals were monitored for 9 months after the surgical procedures, to allow adequate time for reinnervation. The dogs were postoperatively monitored with clinical observation, electrophysiologic testing, video motion analysis, and histologic assessments. Clinical observation and electrophysiologic testing demonstrated the production of an eye blink in the denervated hemi-face in all experimental groups. There was a trend toward increased speed of reinnervation for group III animals (end-to-end coaptations). It was concluded that end-to-side coaptation can produce a contralateral synchronous eye blink in a clinically relevant, large-animal model.

A study of computer-based task performance under thermal stress.

A visual-visual dual computer task was designed to test the effect of the thermal environment on dual task performance. The temperatures selected for testing were 20 and 35 degrees C Wet Bulb Globe Temperature (WBGT). 34 volunteers were randomly assigned to 1 of the 2 temperature conditions. Individual differences in single task performance were controlled by equating the baselines of single task performance. Once individual differences in single task capacity were controlled, statistically significant differences in performance were demonstrated. Mean accuracy was computed over a 1-hr testing period in each temperature condition. Participants' mean accuracy in the 35 degrees condition (38.18%) was substantially lower than in the 20 degrees condition (50.88%).