Effects of Percussive Massage Treatments on Symptoms Associated with Eccentric Exercise-Induced Muscle Damage.

Percussive massage (PM) is an emerging recovery treatment despite the lack of research on its effects post-eccentric exercise (post-EE). This study investigated the effects of PM treatments (immediately, 24, 48, and 72 h post-EE) on the maximal isometric torque (MIT), range of motion (ROM), and an 11-point numerical rating scale (NRS) of soreness of the nondominant arm's biceps brachii from 24-72 h post-EE. Seventeen untrained, college-aged subjects performed 60 eccentric elbow flexion actions with their nondominant arms. Nine received 1 minute of PM, versus eight who rested quietly (control [CON]). In order, NRS, ROM, and MIT (relative to body mass) were collected pre-eccentric exercise (pre-EE) and after treatment (AT) at 24, 48, and 72 h post-EE. NRS was also collected before treatment (BT). Electromyographic (EMG) and mechanomyographic (MMG) amplitudes were collected during the MIT and normalized to pre-EE. There were no interactions for MIT, EMG, or MMG, but there were interactions for ROM and NRS. For ROM, the PM group had higher values than the CON 24-72 h by ~6-8°, a faster return to pre-EE (PM: 48 h, CON: 72 h), and exceeded their pre-EE at 72 h by ~4°. The groups' NRS values did not differ BT 24-72 h; however, the PM group lowered their NRS from BT to AT within every visit by ~1 point per visit, which resulted in them having lower values than the CON from 24-72 h by ~2-3 points. Additionally, the PM group returned their NRS to pre-EE faster than the CON (PM: BT 72 h, CON: never). In conclusion, PM treatments may improve ROM without affecting isometric strength or muscle activation 24-72 h post-EE. Although the PM treatments did not enhance the recovery from delayed onset muscle soreness until 72 h, they consistently provided immediate, temporary relief when used 24-72 h post-EE.

Lower extremity and trunk sagittal plane coordination strategies and kinetic distribution during landing in males and females.

Force attenuation during landing requires coordinated motion of the ankle, knee, hip, and trunk, and strategies may differ between sexes. Sagittal plane coordination of the ankle/knee, knee/hip, and knee/trunk, and lower extremity and trunk kinematics and kinetics was compared throughout landing between 28 males and 28 females. Coordination was assessed with a modified vector coding technique and binning analysis. Total support moments (TSM), each joint's percent contribution, and timing of the TSM were compared. Females landed with less isolated knee flexion in the ankle/knee, knee/hip, and knee/trunk couplings, but more simultaneous ankle/knee flexion, less simultaneous knee flexion/hip extension, and more simultaneous trunk/knee flexion. Females landed with larger plantarflexion angles from 0-16% and smaller trunk flexion angles from 0-78%. In females, absolute TSM were larger from 0-6% and smaller from 42-100%, and normalized TSM were larger from 0-8% and 26-42%. Females had greater ankle contribution to the TSM from 14-15% and 29-35%, smaller absolute peak TSM, and the peak TSM occurred earlier. Females compensated for less isolated knee flexion with greater simultaneous ankle/knee flexion early in landing and knee/trunk flexion later in landing. Coordination and TSM differences may influence force attenuation strategies and have implications for knee injury disparity between sexes.

Lower Body Joint Moments during the Golf Swing in Older Adults: Comparison to Other Activities of Daily Living.

Golf participation has increased dramatically in the last several years. With this increase in participation, clinicians need better evidenced based strategies to advise those golfers with different pathologies when it is safe to return to the game. Golf teaching professionals also need to understand how to alter golf mechanics to protect injured and/or diseased joints in golfers to allow them to play pain free and avoid further injury. This study used a 3-dimensional link segment model to calculate the net joint moments on the large lower limb joints (knee and hip) during golf (lead and trail leg) and two commonly studied activities of daily living (gait and sit-to-stand) in 22 males, healthy, adult golfers. It also examined the correlations between these knee and hip joint loads and club head speed. The external valgus knee moment and the internal hip adduction moment were greater in the lead leg in golf than in the other activities and were also correlated with club head speed. This indicates a strategy of using the frontal plane GRF moment during the swing. The internal hip extension and knee flexion moment were also greater in the golf swing as compared with the other activities and the hip extension moment was also correlated with club head speed. This emphasizes the importance of hip extensor (i.e., gluteus maximus and hamstring) muscle function in golfers, especially in those emphasizing the use of anterior-posterior ground reaction forces (i.e., the pivoting moment). The golf swing places some loads on the knee and the hip that are much different than the loads during gait and sit-to-stand tasks. Knowledge of these golf swing loads can help both the clinician and golf professional provide better evidence-based advice to golfers in order to keep them healthy and avoid future pain/injury.

A Research Note Investigating the Leg Tuck and Plank With Potential Impacts for Occupational Testing.

ABSTRACT: Gonzalez, SM, Withrow, KL, Rubin, DA, Lynn, SK, Dawes, JJ, Orr, RM, and Lockie, RG. A research note investigating the leg tuck and plank with potential impacts for occupational testing. J Strength Cond Res 37(10): 2076-2079, 2023-The U.S. Army recently replaced the leg tuck with the plank in their physical ability testing. There has been limited analysis of whether these 2 tests correlate, have any relationships with body composition and strength, or are sex-neutral. Forty-nine civilian college students (28 males, 21 females) were recruited as surrogates for tactical personnel. The following were measured: height, body mass, body fat percentage (BF%), and muscle mass percentage (MM%) measured through bioelectrical impedance analysis, grip strength, leg tuck, and plank. Independent t -tests were calculated to determine between-sex differences for all variables ( p < 0.05). Partial correlations controlling for sex were used to compute relationships between the leg tuck, plank, and other variables. Stepwise regression controlling for sex derived predictive relationships for the leg tuck and plank. Males were taller, had greater body mass, MM%, and were superior in grip strength and the leg tuck; females had greater BF%. There were no significant between-sex differences for the plank. The leg tuck correlated with BF%, MM%, grip strength, and the plank ( r = ±0.333-0.524). In addition to the leg tuck, the plank correlated with BF% ( r = -0.288). The leg tuck was predicted by sex, grip strength, and the plank (adjusted r2 = 0.662). No variables predicted the plank. As there were no between-sex differences and sex was not a plank predictor, it appears this test minimized sex differences on task performance in civilians. However, the leg tuck and plank likely measure different qualities; further research is needed on job task relationships.

Lower extremity coordination strategies to mitigate dynamic knee valgus during landing in males and females.

Frontal and sagittal plane landing biomechanics differ between sexes but reported values don't account for simultaneous segment or joint motion necessary for a coordinated landing. Frontal and sagittal plane coordination patterns, angles, and moments were compared between 28 males and 28 females throughout the landing phase of a drop vertical jump. Females landed with less isolated thigh abduction (p = 0.018), more in-phase motion (p < 0.001), and more isolated shank adduction (p = 0.028) between the thigh and shank in the frontal plane compared with males. Females landed with less in-phase (p = 0.012) and more anti-phase motion (p = 0.019) between the thigh and shank in the sagittal plane compared with males. Females landed with less isolated knee flexion (p = 0.001) and more anti-phase motion (p < 0.001) between the sagittal and frontal plane knee coupling compared with males. Waveform and discrete metric analyses revealed females land with less thigh abduction from 20 % to 100 % and more shank abduction from 0 to 100 % of landing, smaller knee adduction at initial contact (p = 0.002), greater peak knee abduction angles (p = 0.015), smaller knee flexion angles at initial contact (p = 0.035) and peak (p = 0.034), greater peak knee abduction moments (p = 0.024), greater knee abduction angles from 0 to 13 % and 19 to 30 %, greater knee abduction moments from 19 to 25 %, and smaller knee flexion moments from 3 to 5 % of landing compared with males. Females utilize greater frontal plane motion compared with males, which may be due to different inter-segmental joint coordination and smaller sagittal plane angles. Larger knee abduction angles and greater knee adduction motion in females are due to aberrant shank abduction rather than thigh adduction.

Army Combat Fitness Test Relationships to Tactical Foot March Performance in Reserve Officers' Training Corps Cadets.

The Army Combat Fitness Test (ACFT), consisting of deadlift, standing power throw, hand release push-up, sprint-drag-carry, leg tuck or plank, and 2-mile run, is the United States Army's new fitness test. The ACFT is designed to measure multiple fitness components required to perform combat tasks. One critical task is the tactical foot march (TFM), where soldiers cover long distances while carrying loads comprised of mission-essential equipment. As the ACFT is meant to predict soldier task performance, determining the relationships between the ACFT and the TFM is important. Data from 29 cadets (♂ = 20, ♀ = 9) from one university Reserve Officers' Training Corps program were analyzed. The ACFT was recorded in raw and scaled scores. The TFM was performed over 6.44 km, with time recorded. Cadets carried a 15.88-kg rucksack, fighting load carrier, 3-L hydration pack, and replica M4 carbine. Independent samples t-tests evaluated ACFT and TFM between-sex differences. Partial correlations, controlling for sex, determined ACFT event and TFM relationships. Male cadets outperformed females in all ACFT tasks (p ≤ 0.039), except the push-up. ACFT total score, leg tuck, 2-mile run, and sprint-drag-carry showed large correlations with the TFM (r = ±0.463-0.531, p ≤ 0.026). Aerobic and anaerobic capacity and upper body/trunk strength were important fitness components for cadet TFM performance.

Sex-Specific associations between hip muscle strength and foot progression angle.

The foot progression angle (FPA) influences knee loading during gait, but its determinants are unclear. The purpose of this study was to compare FPA between males and females and also examine the association between lower extremity kinematics during gait, hip strength, and the FPA. 25 males and 25 females completed 5 gait trials while FPA and frontal and transverse plane hip and knee angles were calculated from the dominant limb during the foot flat portion of stance. Hip extensor/flexor, abductor/adductor, and internal/external rotator strength were evaluated using maximum voluntary isometric contractions. One-way MANOVAs compared gait and strength outcomes. Stepwise regression assessed the association between FPA, and MVIC and kinematics after accounting for speed in males and females. There was no difference in FPA between sexes (p > 0.05), but females had greater frontal and transverse plane hip angles compared with males (all p < 0.05). Greater hip abduction (p = 0.02) strength was associated with greater FPA, but only in males. In males, greater hip abductor strength may contribute to a more neutral position of the foot during gait, which could help maintain an equal knee loading distribution. Our results suggest that there are sex specific control strategies to achieve a similar FPA during gait.

Relationships Between Sprint, Acceleration, and Deceleration Metrics with Training Load in Division I Collegiate Women's Soccer Players.

Player load is a variable derived from GPS technology that quantifies external load demands. Sprints and change-of-direction movements are high-intensity activities that place stress on the body. Research is needed to determine which sprint metrics may relate to and predict player load during practice sessions in collegiate women's soccer players, as coaches could manipulate the most impactful variables. This study analyzed which sprint metrics related to GPS player load in women's soccer players from one Division I team. Data from 19 practice sessions for 18 field players were analyzed. Players wore GPS sensors during all training sessions, and the variables assessed were player load, sprint count, sprint volume, sprint distance, average top speed, maximum top speed, and the number of accelerations and decelerations in different speed zones (±1, ±2, ±3, ±4, ±5 m/s2). Pearson's correlations (p < 0.05) analyzed relationships between the sprint variables and player load. Stepwise regression analyses (p < 0.05) determined if any metrics predicted player load. The results indicated significant relationships between player load and sprint count, maximum top speed, sprint distance, sprint volume, number of decelerations at -1, -2, and -3 m/s2, and accelerations at 1, 2, and 5 m/s2(r = 0.512-0.861, p ≤ 0.025). Sprint distance and decelerations at 1 m/s2predicted player load (p = 0.001, r2= 0.867). Maximal sprinting and decelerations and accelerations at different speeds were significant contributors to player load in collegiate women's soccer players. Sprint distance, decelerations, and accelerations could be targeted in training drills via dimension and movement manipulation to adjust training intensity for collegiate women's soccer players.

Comparison of Lower Extremity Kinematics during the Overhead Deep Squat by Functional Movement Screen Score.

It is unclear if the Functional Movement Screen (FMS) scoring criteria identify kinematics that have been associated with lower extremity injury risk. The purpose was to compare lower extremity kinematics of the overhead deep squat (OHDS) during the FMS between individuals who were grouped on FMS scoring. Forty-five adults who were free of injury and without knowledge of the FMS or its scoring criteria (males = 19, females = 26; height = 1.68 0.08 m; mass = 70.7 7 13.0 kg). Three-dimensional lower extremity kinematics during an OHDS were measured using a motion capture system. One-way MANOVA was used to compare kinematic outcomes (peak hip flexion angle, hip adduction angle, knee flexion angle, knee abduction angle, knee internal rotation angle, and ankle dorsiflexion angle) between FMS groups. Those who scored a 3 had greater peak hip flexion angle (F2,42 = 8.75; p = 0.001), knee flexion angle (F2,42 = 13.53; p = 0.001), knee internal rotation angle (F2,42 = 12.91; p = 0.001), and dorsiflexion angle (F2,42 = 9.00; p = 0.001) compared to those who scored a 2 or a 1. However, no differences were found in any outcome between those who scored a 2 and those who scored a 1, or in frontal plane hip or knee kinematics. FMS scoring for the OHDS identified differences in squat depth, which was characterized by larger peak hip, knee, and dorsi- flexion angles in those who scored a 3 compared with those who scored 2 or 1. However, no differences were found between those who scored a 2 or 1, and caution is recommended when interpreting these scores. Despite a different FMS score, few differences were observed in frontal or transverse plane hip and knee kinematics, and other tasks may be needed to assess frontal plane kinematics.

Foot Rotation Gait Modifications Affect Hip and Ankle, But Not Knee, Stance Phase Joint Reaction Forces During Running.

Alterations of foot rotation angles have successfully reduced external knee adduction moments during walking and running. However, reductions in knee adduction moments may not result in reductions in knee joint reaction forces. The purpose of this study was to examine the effects of internal and external foot rotation on knee, hip, and ankle joint reaction forces during running. Motion capture and force data were recorded of 19 healthy adults running at 3.35 m/s during three conditions: (1) preferred (normal) and with (2) internal and (3) external foot rotation. Musculoskeletal simulations were performed using opensim and the Rajagopal 2015 model, modified to a two degree-of-freedom knee joint. Muscle excitations were derived using static optimization, including muscle physiology parameters. Joint reaction forces (i.e., the total force acting on the joints) were computed and compared between conditions using one-way analyses of variance (ANOVAs) via statistical parametric mapping (SPM). Internal foot rotation reduced resultant hip forces (from 18% to 23% stride), while external rotation reduced resultant ankle forces (peak force at 20% stride) during the stance phase. Three-dimensional and resultant knee joint reaction forces only differed at very early and very late stance phase. The results of this study indicate, similar to previous findings, that reductions in external knee adduction moments do not mirror reductions in knee joint reaction forces.

Validity and Reliability of Surface Electromyography Measurements from a Wearable Athlete Performance System.

The Athos ® wearable system integrates surface electromyography (sEMG ) electrodes into the construction of compression athletic apparel. The Athos system reduces the complexity and increases the portability of collecting EMG data and provides processed data to the end user. The objective of the study was to determine the reliability and validity of Athos as compared with a research grade sEMG system. Twelve healthy subjects performed 7 trials on separate days (1 baseline trial and 6 repeated trials). In each trial subjects wore the wearable sEMG system and had a research grade sEMG system's electrodes placed just distal on the same muscle, as close as possible to the wearable system's electrodes. The muscles tested were the vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF). All testing was done on an isokinetic dynamometer. Baseline testing involved performing isometric 1 repetition maximum tests for the knee extensors and flexors and three repetitions of concentric-concentric knee flexion and extension at MVC for each testing speed: 60, 180, and 300 deg/sec. Repeated trials 2-7 each comprised 9 sets where each set included three repetitions of concentric-concentric knee flexion-extension. Each repeated trial (2-7) comprised one set at each speed and percent MVC (50%, 75%, 100%) combination. The wearable system and research grade sEMG data were processed using the same methods and aligned in time. The amplitude metrics calculated from the sEMG for each repetition were the peak amplitude, sum of the linear envelope, and 95th percentile. Validity results comprise two main findings. First, there is not a significant effect of system (Athos or research grade system) on the repetition amplitude metrics (95%, peak, or sum). Second, the relationship between torque and sEMG is not significantly different between Athos and the research grade system. For reliability testing, the variation across trials and averaged across speeds was 0.8%, 7.3%, and 0.2% higher for Athos from BF, VL and VM, respectively. Also, using the standard deviation of the MVC normalized repetition amplitude, the research grade system showed 10.7% variability while Athos showed 12%. The wearable technology (Athos) provides sEMG measures that are consistent with controlled, research grade technologies and data collection procedures.

Lower-Limb Dominance, Performance, and Fiber Type in Resistance-trained Men.

INTRODUCTION: Large imbalances between limbs are common and potentially dangerous, yet few studies have simultaneously examined performance and physiological asymmetries. The current study examined the associations between lower-limb dominance, drop-jumping kinematics, maximal strength, and myosin heavy-chain (MHC) fiber type in the vastus lateralis. METHODS: Thirteen resistance-trained men (age, 24.3 ± 2.7 yr; height, 181.4 ± 6.6 cm; mass, 87.7 ± 11.3 kg) identified their dominant (DOM) and nondominant (ND) limb, performed drop jumps (30 cm) and maximal knee extensions (1-repetition maximum, or 1RM), and provided biopsies from both vastus lateralis muscles for single-fiber (109 ± 36 per limb per person) MHC fiber-type identification (FT%). RESULTS: All participants selected "right" as the "preferred kicking limb" (DOM). DOM displayed a trend for a greater eccentric knee angular velocity (EKV; P = 0.083) and a significantly greater concentric knee angular velocity (CKVl P = 0.002) during drop jump. DOM also tended to be stronger than ND (64.3 ± 11.3 vs 61.0 ± 8.8 kg, P = 0.063). Slow-twitch (MHC I) fibers were more prevalent in DOM (P < 0.025), whereas ND contained more fast-twitch (MHC IIa; P < 0.025). No correlations existed between categories (jumping, 1RM, and FT%). Asymmetries of >5% were present in 6 of 12 participants for EKV, 2 of 12 for CKV, 6 of 13 for 1RM, 12 of 13 for MHC I, and 11 of 13 for MHC IIa. However, only a single participant expressed asymmetries of >5% in all dependent variables (EKV, CKV, 1RM, MHC I, and MHC IIa). CONCLUSIONS: Several statistically and clinically relevant asymmetries were identified. The FT% differences between lower limbs were large and common. The findings also seem to conclude that DOM was stronger, moved faster, and contained more MHC I. However, only 23% of participants actually displayed that result. This highlights the need to analyze and report both group and individual data, particularly when interpreting findings across multiple related, but not necessarily causal, measurements.

A prospective comparison of lower extremity kinematics and kinetics between injured and non-injured collegiate cross country runners.

Collegiate cross country runners are at risk for running related injuries (RRI) due to high training volume and the potential for aberrant lower extremity biomechanics. However, there is a need for prospective research to determine biomechanical risk factors for RRI. The purpose of this study was to prospectively compare ankle, knee, and hip kinematics and kinetics and ground reaction force characteristics between injured and non-injured cross country runners over a 14-week season. Biomechanical running analyses were conducted on 31 collegiate-cross country runners using a 3-dimensional motion capture system and force plate prior to the start of the season. Twelve runners were injured and 19 remained healthy during the course of the season. Peak external knee adduction moment (KAM), a surrogate for frontal plane knee loading, and peak ankle eversion velocity were greater in runners who sustained an injury compared to those who did not, and no differences were noted in ground reaction force characteristics, or hip kinematics and kinetics. Reducing the KAM and ankle eversion velocity may be an important aspect of preventing RRI.

Acute Effects of Foot Rotation in Healthy Adults during Running on Knee Moments and Lateral-Medial Shear Force.

As runners age, the likelihood of developing osteoarthritis (OA) significantly increases as 10% of people 55+ have symptomatic knee OA while 70% of people 65+ have radiographic signs of knee OA. The lateral-medial shear force (LMF) and knee adduction moment (KAM) during gait have been associated with cartilage loading which can lead to OA. Foot rotation during gait has been shown to alter the LMF and KAM, however it has not been investigated in running. The purpose of this study was to investigate changes in the KAM and LMF with foot rotation during running. Twenty participants volunteered and performed five running trials in three randomized conditions (normal foot position [NORM], external rotation [EXT], and internal rotation [INT]) at a running speed of 3.35m·s(-1) on a 20 meter runway. Kinematic and kinetic data were gathered using a 9-camera motion capture system and a force plate, respectively. Repeated measures ANOVAs determined differences between conditions. The KAM and LMF were lower in both EXT and INT conditions compared to the NORM, but there were no differences between EXT and INT conditions. The decreases in KAM and LMF in the EXT condition were expected and concur with past research in other activities. The reductions in the INT condition were unexpected and contradict the literature. This may indicate that participants are making mechanical compensations at other joints to reduce the KAM and LMF in this abnormal internal foot rotation condition. Key pointsExternal rotation of the foot during running reduced the loads on the medial compartment of the kneeInternal rotation of the foot also reduced the medial loads, but is a more unnatural interventionExternal and internal rotation reduced the shear forces on the knee, which may help slow the degeneration of knee joint cartilage.

Electromyographic and Force Plate Analysis of the Deadlift Performed With and Without Chains.

The purpose of this study was to determine the effects of deadlift chain variable resistance on surface electromyography (EMG) of the gluteus maximus, erector spinae, and vastus lateralis muscles, ground reaction forces (GRFs), and rate of force development (RFD). Thirteen resistance-trained men (24.0 ± 2.1 years, 179.3 ± 4.8 cm, 87.0 ± 10.6 kg) volunteered for the study. On day 1, subjects performed 1 repetition maximum (1RM) testing of the deadlift exercise. On day 2, subjects performed one set of 3 repetitions with a load of 85% 1RM with chains (CH) and without chains (NC). The order of the CH and NC conditions was randomly determined for each subject. For the CH condition, the chains accounted for approximately 20% (19.9 ± 0.6%) of the 85% 1RM load, matched at the top of the lift. Surface EMG was recorded to differentiate muscle activity between conditions (CH, NC), range of motion (ROM; bottom, top), and phase (concentric, eccentric). Peak GRFs and RFD were measured using a force plate. Electromyography results revealed that for the gluteus maximus there was significantly greater EMG activity during the NC condition vs. the CH condition. For the erector spinae, EMG activity was greater at the bottom than the top ROM (p ≤ 0.05). Force plate results revealed that deadlifting at 85% 1RM with an accommodating chain resistance of approximately 20% results in a reduction in GRFs (p ≤ 0.05) and no change in RFD (p > 0.05). Collectively, these results suggest that the use of chain resistance during deadlifting can alter muscle activation and force characteristics of the lift.

Bench Press Upper-Body Muscle Activation Between Stable and Unstable Loads.

The bench press is one of the most commonly used upper-body exercises in training and is performed with many different variations, including unstable loads (ULs). Although there is much research on use of an unstable surface, there is little to none on the use of an UL. The purpose of this study was to investigate muscle activation during the bench press while using a stable load (SL) vs. UL. Twenty resistance-trained men (age = 24.1 ± 2 years; ht = 177.5 ± 5.8 cm; mass = 88.7 ± 13.7 kg) completed 2 experimental conditions (SL and UL) at 2 different intensities (60 and 80% one repetition maximum). Unstable load was achieved by hanging 16 kg kettlebells by elastic bands from the end of the bar. All trial lifts were set to a 2-second cadence with a slight pause at the bottom. Subjects had electrodes attached to 5 muscles (pectoralis major, anterior deltoid, medial deltoid, triceps brachii, and latissimus dorsi) and performed 3 isometric bench press trials to normalize electromyographic data. All 5 muscles demonstrated significantly greater activation at 80% compared with 60% load and during concentric compared with eccentric actions. These results suggest that upper body muscle activation is not different in the bench press between UL and SL. Therefore, coaches should use their preference when designing training programs.

Ankle dorsiflexion may play an important role in falls in women with fibromyalgia.

BACKGROUND: Fibromyalgia is a chronic pain condition, which involves reduced range of motion. This leads to gait changes and high incidence of falls. The understanding of the gait patterns in subjects with fibromyalgia and their relationship with falls may be useful when designing intervention programs. The purpose of this study was to evaluate the range of motion of the hip and ankle joints during gait in women with and without fibromyalgia. Further, we determined the relationship between joint range of motion and falls in this population. METHODS: Middle-aged women (16 with fibromyalgia and 16 as control group) were recruited. Pain intensity, physical activity level, and fall prevalence were assessed. Three dimensional gait analysis provided temporal and joint kinematic variables. FINDINGS: In general, hip and ankle range of motion were similar between groups, except that fibromyalgia group showed higher plantar flexion during toe-off (P<0.05) and reduced dorsiflexion during stance phase (P<0.05). Additionally, in the fibromyalgia group the higher number of falls was correlated to reduced dorsiflexion during stance phase. This limitation in dorsiflexion was related to longer length of time with fibromyalgia symptoms. INTERPRETATION: Women with fibromyalgia showed a higher number of falls, reduced dorsiflexion during stance phase, and increased plantar flexion during toe-off. Also, the higher number of falls reported in the fibromyalgia group was related to reduced dorsiflexion during stance phase, which was correlated to a longer length of time living with fibromyalgia symptoms. These data suggest that improving ankle kinematics in patients with fibromyalgia may help prevent falls and improve mobility.

Effect of Acute Alterations in Foot Strike Patterns during Running on Sagittal Plane Lower Limb Kinematics and Kinetics.

The purpose of this study was to determine the effect of foot strike patterns and converted foot strike patterns on lower limb kinematics and kinetics at the hip, knee, and ankle during a shod condition. Subjects were videotaped with a high speed camera while running a 5km at self-selected pace on a treadmill to determine natural foot strike pattern on day one. Preferred forefoot group (PFFG, n = 10) and preferred rear foot group (PRFG, n = 11) subjects were identified through slow motion video playback (n = 21, age = 22.8±2.2 years, mass = 73.1±14.5 kg, height 1.75 ± 0.10 m). On day two, subjects performed five overground run trials in both their natural and unnatural strike patterns while motion and force data were collected. Data were collected over two days so that foot strike videos could be analyzed for group placement purposes. Several 2 (Foot Strike Pattern -forefoot strike [FFS], rearfoot strike [RFS]) x 2 (Group - PFFG, PRFG) mixed model ANOVAs (p < 0.05) were run on speed, active peak vertical ground reaction force (VGRF), peak early stance and mid stance sagittal ankle moments, sagittal plane hip and knee moments, ankle dorsiflexion ROM, and sagittal plane hip and knee ROM. There were no significant interactions or between group differences for any of the measured variables. Within subject effects demonstrated that the RFS condition had significantly lower (VGRF) (RFS = 2.58 ± .21 BW, FFS = 2.71 ± 0.23 BW), dorsiflexion moment (RFS = -2.6 1± 0.61 Nm·kg(-1), FFS = -3.09 ± 0.32 Nm·kg(-1)), and dorsiflexion range of motion (RFS = 17.63 ± 3.76°, FFS = 22.10 ± 5.08°). There was also a significantly higher peak plantarflexion moment (RFS = 0.23 ± 0.11 Nm·kg(-1), FFS = 0.01 ± 0.01 Nm·kg(-1)), peak knee moment (RFS = 2.61 ± 0.54 Nm·kg(-1), FFS = 2.39 ± 0.61 Nm·kg(-1)), knee ROM (RFS = 31.72 ± 2.79°, FFS = 29.58 ± 2.97°), and hip ROM (RFS = 42.72 ± 4.03°, FFS = 41.38 ± 3.32°) as compared with the FFS condition. This research suggests that acute changes in foot strike patterns during shod running can create alterations in certain lower limb kinematic and kinetic measures that are not dependent on the preferred foot strike pattern of the individual. This research also challenges the contention that the impact transient spike in the vertical ground reaction force curve is only present during a rear foot strike type of running gait. Key pointsFootstrike pattern changes should be individually considered and implemented based on individual histories/abilitiesForefoot strike patterns increase external dorsiflexion momentsRearfoot strike patterns increase external knee flexion momentsRecreational shod runners are able to mimic habitual mechanics of different foot strike patterns.

Differences in static- and dynamic-balance task performance after 4 weeks of intrinsic-foot-muscle training: the short-foot exercise versus the towel-curl exercise.

CONTEXT: Proper functioning of the intrinsic foot musculature (IFM) is essential in maintaining the integrity of the medial longitudinal arch (MLA). Improper functioning of the IFM leads to excessive pronation of the foot, which has been linked to various pathologies. Therefore, training the IFM to avoid excessive pronation may help prevent some of these pathologies; however, it is not clear how to train these muscles optimally. OBJECTIVE: To investigate the effects of 2 different types of IFM training on the height of the MLA and static- and dynamic-balance task performance. DESIGN: Randomized controlled trial, repeated-measures mixed-model design. SETTING: University biomechanics laboratory for testing and a home-based training program. PARTICIPANTS: 24 healthy, university-age volunteers (3 groups of 8) with no history of major lower limb pathology or balance impairment. INTERVENTIONS: One experimental group performed 4 wk of the short-foot exercise (SFE) and the other performed 4 wk of the towel-curl exercise (TCE). Participants were asked to perform 100 repetitions of their exercise per day. MAIN OUTCOME MEASURES: Navicular height during weight bearing, the total range of movement of the center of pressure (COP) in the mediolateral (ML) direction for a static-balance test and a dynamic-balance test. RESULTS: There were no differences in the navicular height or static-balance tests. For the dynamic-balance test, all groups decreased the ML COP movement on the dominant limb by a small amount (~5 mm); however, the SFE group was able to decrease COP movement much more than the TCE group in the nondominant limb. CONCLUSIONS: The SFE appeared to train the IFM more effectively than the TCE; however, there were differing results between the dominant and nondominant legs. These imbalances need to be taken into consideration by clinicians.

Effects of assisted jumping on vertical jump parameters.

Vertical jumping ability is a critical skill for success in many sports. Previous studies have reported conflicting results on the effects of heavy-load, light-load, contrast, or plyometric training to improve vertical jump height. A novel jump training method, using assistance via elastic cords or an absolute weight, has received little attention. These studies, using an overspeed paradigm, support assistance as an effective training method compared with free or overload jump training. However, there is a lack of investigation and standardization related to the critical assisted jump training variables of frequency, intensity (assistance level), volume, and rest. Therefore, the purpose of this review was to provide an overview of assisted jump training, associated variables, and potential benefits to enhance vertical jump height.