Habitual physical activity and COVID-19.

Background: Physical activity (PA) is known to decrease COVID-19 risk factors and can attenuate symptoms of viral infections. However, difficulty exercising and fatigue are common complaints after COVID-19. It is unknown whether prior habitual PA will improve outcomes and what the time course is until full recovery of PA after COVID-19.

Lower extremity kinematic and kinetic factors associated with bat speed at ball contact during the baseball swing.

The purpose of this study was to determine which biomechanical variables measured during the baseball swing are associated with linear bat speed at ball contact (bat speed). Twenty collegiate baseball players hit a baseball from a tee into a net. Kinematics were recorded with a motion capture system sampling at 500 Hz and kinetics were measured by force plates under each foot sampling at 1000 Hz.

Incidence of concussions and helmet use in equestrians.

Objectives: Equestrians have a high risk of concussions per hospital records. However, most concussions occur in private settings where concussions are not tracked. We determined concussion incidence by self-report, expressed per 1000 h of exposure, and determined helmet usage and concussion knowledge.

Role of Pelvis and Trunk Biomechanics in Generating Ball Velocity in Baseball Pitching.

Orishimo, KF, Kremenic, IJ, Mullaney, MJ, Fukunaga, T, Serio, N, and McHugh, MP. Role of pelvis and trunk biomechanics in generating ball velocity in baseball pitching. J Strength Cond Res 37(3): 623-628, 2023-The purpose of this study was to determine the impact of pelvis rotation velocity, trunk rotation velocity, and hip-shoulder separation on ball velocity during baseball pitching.

Importance of Transverse Plane Flexibility for Proficiency in Golf.

McHugh, MP, O'Mahoney, CA, Orishimo, KF, Kremenic, IJ, and Nicholas, SJ. Importance of transverse plane flexibility for proficiency in golf. J Strength Cond Res 36(2): e49-e54, 2022-The extent to which the flexibility requirements for golf proficiency vary between the planes of motion has not been examined.

Comparison of Hip and Low Back Loads between Normal Gait, Axillary Crutch Ambulation and Walking with a Hands-free Crutch in a Healthy Population.

Background: Instead of using axillary crutches, using a hands-free crutch (HFC) has been associated with higher functional outcome scores. However, hip and back pain have been reported as side effects.

Purpose/hypothesis: The purpose of this study was to compare range of motion and joint reaction forces at the hip and low back between HFC walking, normal walking, and standard crutch walking.

Motion of the multi-segmented spine in elite dancers during passé and arabesque.

Background: The spinal biomechanics of dance tasks have received little study and no studies have used a multi-segmented spinal model. Knowledge of how the segments of the spine move may be useful to the dance clinician and dance educator.

Research Question: What is the direction and amount of motion of the primary segments of the spine in elite dancers during an arabesque and a passé?

Methods: This observational study examined 59 elite dancers performing an arabesque and a passé using a three-dimensional motion analysis system with the trunk divided into a series of five segments: pelvis, lower lumbar, upper lumbar, lower thoracic and upper thoracic spine.

Electromyographic Evidence of Excessive Achilles Tendon Elongation During Isometric Contractions After Achilles Tendon Repair.

Background: Weakness in end-range plantarflexion has been demonstrated after Achilles tendon repair and may be because of excessive tendon elongation. The mean frequency (MNF) of surface electromyogram (EMG) data during isometric maximum voluntary contraction (MVC) increases with muscle fiber shortening.

Hypothesis: During isometric plantarflexion, MNF during MVCs will be higher on the involved side compared with the uninvolved side after Achilles tendon repair because of excessive tendon elongation and greater muscle fiber shortening.

Multi-segment spine range of motion in dancers with and without recent low back pain.

Background: Altered spine kinematics are a common in people with LBP. This may be especially true for populations such as dancers, who are required to perform repetitive movements of the spine, although this remains unclear.

Research Question: Do dancers with recent LBP display altered spine kinematics compared to their asymptomatic counterparts?

Methods: A cross-sectional study of multi-segment spine kinematics was performed.

Effect of carbohydrate beverage ingestion on central versus peripheral fatigue: a placebo-controlled, randomized trial in cyclists.

We investigated whether carbohydrate ingestion delays fatigue in endurance-trained cyclists via peripheral or central mechanisms. Ten men (35 ± 9 years of age) and 10 women (42 ± 7 years of age) were assigned, in a double-blind, crossover design, to a sports drink (CHO) or to a placebo (PL). The following strength measures were made 3 times (before exercise, after a time trial (TT), and after a ride to exhaustion): (i) maximal voluntary contraction (MVC); (ii) MVC with superimposed femoral nerve magnetic stimulation to measure central activation ratio (CAR); and (iii) femoral nerve stimulation in a 3-s pulse train on relaxed muscle.

Countermovement Jump Recovery in Professional Soccer Players Using an Inertial Sensor.

Purpose: To assess the utility of an inertial sensor for assessing recovery in professional soccer players.

Methods: In a randomized, crossover design, 11 professional soccer players wore shorts fitted with phase change material (PCM) cooling packs or uncooled packs (control) for 3 h after a 90-min match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system: prematch and 12, 36, and 60 h postmatch.

EMG OF SHOULDER MUSCLES DURING REACTIVE ISOMETRIC ELASTIC RESISTANCE EXERCISES.

Background: Traditionally, shoulder isometrics are introduced in the early stages of shoulder rehabilitation. A patient's isometric torque output is based on a subjective perception of force generation. By utilizing elastic resistance elongation (strain) to standardize force output, clinicians could prescribe shoulder therapeutic isometrics based on % maximum voluntary contraction (%MVC).

The 2- and 8-week effects of decompressive brace use in people with medial compartment knee osteoarthritis.

Background: Knee osteoarthritis is a prevalent disease. Unloading the affected compartment using a brace is a treatment option.

Objectives: To determine whether a decompressive knee brace alters loading in medial knee osteoarthritis following 2 and 8 weeks of use.

Restoring Isometry in Lateral Ulnar Collateral Ligament Reconstruction.

Purpose: To ascertain whether placing the humeral attachment of the lateral ulnar collateral ligament (LUCL) at the humeral center of rotation (hCOR) on the humerus would provide the most isometric reconstruction.

Methods: We analyzed 13 cadaver limbs from mid-humerus to the hand. The morphology of the ligament complex was assessed.

Comparison of landing biomechanics between male and female dancers and athletes, part 2: Influence of fatigue and implications for anterior cruciate ligament injury.

Background: Fatigue is strongly linked to an increased risk of injuries, including anterior cruciate ligament (ACL) ruptures. Part 1 of this study identified differences in the biomechanics of landing from a jump between dancers and team athletes, particularly female athletes, which may explain the epidemiological differences in ACL injuries between dancers and team athletes and the lack of a sex disparity within dancers. However, it is not known if these biomechanical variables change differently between team athletes and dancers in the face of fatigue.

Comparison of landing biomechanics between male and female dancers and athletes, part 1: Influence of sex on risk of anterior cruciate ligament injury.

Background: The incidence of anterior cruciate ligament (ACL) injuries among dancers is much lower than among team sport athletes, and no clear disparity between sexes has been reported in the dance population. Although numerous studies have observed differences in landing biomechanics of the lower extremity between male and female team sport athletes, there is currently little research examining the landing biomechanics of male and female dancers and none comparing athletes to dancers. Comparing the landing biomechanics within these populations may help explain the lower overall ACL injury rates and lack of sex disparity.

Similar improvement in gait parameters following direct anterior & posterior approach total hip arthroplasty.

We compared gait parameters prior to, at 6 months and 1 year following total hip arthroplasty (THA) performed via direct anterior approach (DAA) and posterior approach (PA) by a single surgeon in 22 patients. A gait analysis system involving reflective markers, infrared cameras and a multicomponent force plate was utilized. Postoperatively, the study cohort demonstrated improvement in flexion/extension range of motion (ROM) (P = 0.

What is known about the effect of fatigue on injury occurrence among dancers?

Fatigue is often thought of as any transient exercise-induced reduction of work capacity. In fact, it is a complex phenomenon caused by overlapping and interacting peripheral and central mechanisms. There is a known relationship between fatigue, diminished performance, and injury.

Sex differences in central and peripheral mechanisms of fatigue in cyclists.

We examined peripheral versus central contributions to fatigue in men and women during prolonged cycling using a peripheral nerve magnetic stimulation-based technique. 11 men (41 ± 3 years) and 9 women (38 ± 2 years) cycled for 2 h at ventilatory threshold with 5, 1-min sprints interspersed, followed by a 3-km time trial. Quadriceps strength testing was performed isometrically in a semi-reclined position pre- and post-cycling: (1) MVC; (2) MVC with superimposed 3-s magnetic stimulation to measure central activation ratio (CAR), a measure of central fatigue; (3) peripheral magnetic stimulation (PMS) alone of the femoral nerve in a 4-s pulse train, a measure of peripheral fatigue.

Electromyographic analysis of the triceps surae muscle complex during achilles tendon rehabilitation program exercises.

Background: Specific guidelines for therapeutic exercises following an Achilles tendon repair are lacking.

Hypothesis: A hierarchical progression of triceps surae exercises can be determined on the basis of electromyographic (EMG) activity.

Study Design: Randomized laboratory trial.

Is valgus unloader bracing effective in normally aligned individuals: implications for post-surgical protocols following cartilage restoration procedures.

Purpose: Utilizing valgus unloader braces to reduce medial compartment loading in patients undergoing cartilage restoration procedures may be an alternative to non-weightbearing post-operative protocols in these patients. It was hypothesized that valgus unloader braces will reduce knee adduction moment during the stance phase in healthy subjects with normal knee alignment.

Methods: Gait analysis was performed on twelve adult subjects with normal knee alignment and no history of knee pathology.

The effects of floor incline on lower extremity biomechanics during unilateral landing from a jump in dancers.

Retrospective studies have suggested that dancers performing on inclined ("raked") stages have increased injury risk. One study suggests that biomechanical differences exist between flat and inclined surfaces during bilateral landings; however, no studies have examined whether such differences exist during unilateral landings. In addition, little is known regarding potential gender differences in landing mechanics of dancers.