Lower-Extremity Energetic Distribution During Rate-Controlled Ballet Jumps (Sautés) in Healthy Dancers.

Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés) before and after typical dance-specific choreography. Lower-extremity kinetic data were collected from 14 healthy female dancers during a series of sautés performed before and after 3 minutes of dance. Percent contributions of the lower-extremity joints to the whole-limb mechanical energy expenditure during ground contact were calculated. The jumps performed at the beginning were compared with the jumps at the end of the dance choreography. Dancers maintained the jump rate and consistent whole-limb mechanical energy expenditure between the jump series. As expected, for both jump series, the sautés had greater relative energetic contribution from the ankle and knee as compared with lesser contribution from the hip and toe. However, we observed lesser contribution from the knee and greater contribution from the hip after a 3-minute dance. After performing typical dance choreography, the dancers demonstrated a distal to proximal redistribution of individual joints' contribution to whole-limb mechanical energy expenditure.

Young adults with recurrent low back pain demonstrate altered trunk coordination during gait independent of pain status and attentional demands.

Pain influences both attention and motor behavior. We used a dual-task interference paradigm to investigate (1) alterations in attentional performance, (2) the ability to switch task prioritization, and (3) the effect of attentional demand on trunk coordination during narrow-based walking in and out of a painful episode in individuals with recurrent low back pain (LBP). We tested twenty young adults with LBP both in and out of a painful episode and compared them to twenty matched back-healthy individuals. Participants simultaneously performed a narrow step width matching task and an arithmetic task, with and without instructions to prioritize either task. A motion capture system was used to record kinematic data, and frontal plane trunk coordination was analyzed using vector coding on the thorax and pelvis angles. Single-task performance, dual-task effect, dual-task performance variability, task prioritization switch, and trunk coordination were analyzed using paired t tests or repeated measures two-way ANOVAs. Results indicated that active pain has a detrimental effect on attentional processes, indicated by poorer single-task performance and increased dual-task performance variability for individuals with recurrent LBP. Individuals with LBP, regardless of pain status, were able to switch task prioritization to a similar degree as their back-healthy counterparts. Compared to the control group, individuals with recurrent LBP exhibited a less in-phase, more pelvis-dominated trunk coordination during narrow-based walking, independent of pain status and regardless of attentional manipulations. Thus, altered trunk coordination in persons with LBP appears to be habitual, automatic, and persists beyond symptom duration.

What goes up must come down, part II: Consequences of jump strategy modification on dance leap landing biomechanics.

Knee injuries are common in jumping athletes; modifying jump strategy may impact loads placed on the body and reduce injury risk. The purpose of this study was to determine if modifying strategy in a saut de chat leap to focus on height would decrease sagittal plane knee loading. Biomechanical data were collected while 28 dancers performed saut de chat leaps with instructions to jump far (FAR) or jump high (UP). In the UP condition, there was greater vertical GRF and less braking GRF. Also in UP, lower extremity contact angle was greater (71.3 ± 2.9º FAR; 75.8 ± 3.3º UP; p = 0.0178), peak knee extensor moment was greater (2.8 ± 0.7 Nm FAR; 3.2 ± 0.8 Nm UP; p = 0.01), and peak ankle plantar flexor moment was lower (3.19 ± 0.4 Nm FAR; 2.94 ± 0.4 Nm UP; p < 0.01). A more acute LECA was related to greater braking force and braking force was related to greater knee extensor moments. Despite these relationships, we observed greater knee extensor moments in UP. While the relationship among these whole-body variables and knee joint loading exists, it may not be the primary factor driving load distribution during dance leap landings.

Lower Limb Takeoff Mechanics During a Leap in Dancers With and Without Flexor Hallucis Longus Tendinopathy.

OBJECTIVE: Altered ground reaction force (GRF) and joint torsional stiffness are associated with various lower extremity injuries, but these have yet to be examined in dancers with flexor hallucis longus (FHL) tendinopathy. Additionally, a simple, field-friendly kinematic correlate to ground contact kinetics would be useful for clinical application. The purpose of this study was to compare lower extremity biomechanics during takeoff of a dance leap (saut de chat) in dancers with and without FHL tendinopathy, and to examine lower limb posture at initial contact as a clinical correlate of injury-related kinetic factors. METHODS: Motion capture and inverse dynamics were used to analyze saut de chat takeoff performed by 11 uninjured dancers and 8 dancers with FHL tendinopathy. GRF parameters, joint torsional stiffness of the metatarsophalangeal, ankle, and knee joints, and lower extremity posture at initial contact were compared between groups using Welch's t-tests. RESULTS: Dancers with FHL tendinopathy maintained similar jump height as the uninjured dancers, but exhibited lower peak vertical GRF, longer time to peak force, and less joint torsional stiffness at the metatarsophalangeal, ankle, and knee joints during loading response of the takeoff step. Lower extremity contact angle was smaller and the horizontal distance between center-of-mass and center-of-pressure was greater in dancers with FHL tendinopathy. These two measures of lower limb posture at initial contact were significantly correlated with kinetic factors occurring later in ground contact (R2=0.29-0.51). CONCLUSION: Dancers with FHL tendinopathy demonstrated altered lower extremity kinetics during takeoff of a leap compared to uninjured dancers, which may contribute to, or be a compensation response to, injury.

Persons in remission from recurrent low back pain alter trunk coupling under dual-task interference during a dynamic balance task.

This study investigated effects of cognitive dual-task interference and task prioritization instructions on task performance and trunk control during a dynamic balance task in persons with and without recurrent low back pain (rLBP). First, we tested the hypothesis that those with rLBP rely more on cognitive resources than back-healthy controls, and therefore trunk kinematics would be altered under dual-task interference conditions. Then, we tested participants' ability to modulate task performance in accord with prioritization instructions. Persons with and without rLBP (n = 19/group) performed the Balance-Dexterity Task, which involved single-limb balance while compressing an unstable spring with the other limb, with and without a cognitive task engaging verbal working memory. Trunk coupling was quantified with the coefficient of determination (R2) of an angle-angle plot of thorax-pelvis frontal plane motion. Task performance was quantified using variability of spring compression force and of cognitive task errors. Trunk coupling in the rLBP group was lower than that of the back-healthy control group in the single-task condition (p = 0.024) and increased in the dual-task condition (p = 0.006), abolishing the difference between groups. Significant main effects of task prioritization instruction on performance were observed with no differences between groups, indicating similar performance modulation. Cognitive task error variability decreased with a switch from a single- to dual-task condition, exposing an unexpected facilitation effect. We interpret these findings in the context of movement-specific reinvestment and action-specific perception theories as they pertain to cognitive contributions to posture and how the dual-task interference paradigm may influence those contributions.

What goes up must come down: Consequences of jump strategy modification on dance leap take-off biomechanics.

Chronic foot and ankle injuries are common in dancers; understanding how lower extremity loading changes in response to altered task goals can be beneficial for rehabilitation and injury prevention strategies. The purpose of this study was to examine mechanical demands during jump take-offs when the task goal was modified to focus on either increasing jump distance or increasing jump height. It was hypothesized that a jump strategy focused on height would result in decreased energetic demands on the foot and ankle joints. Thirty healthy, experienced female dancers performed saut de chat leaps while travelling as far as possible (FAR) or jumping as high as possible (UP). Ground reaction force (GRF) impulses and peak sagittal plane net joint moments and sagittal plane mechanical energy expenditure (MEE) of the metatarsophalangeal (MTP), ankle, knee, and hip joints were calculated. During take-off, vertical and horizontal braking GRF impulses were greater and horizontal propulsive GRF impulse was lower in the UP condition. MEE at the MTP, ankle, and hip joints was lower in UP, and MEE at the knee was higher in UP. These results suggest that a strategy focused on height may be helpful in unloading the ankle and MTP joints during dance leaps.

Achieving the Split Position in a Saut de Chat Leap.

OBJECTIVES: Dancers frequently perform complex jumping skills that involve achieving specific body positions while in the air. An examination of how skilled dancers achieve these aesthetic demands can provide information useful for dance training. The purpose of this study was to examine the temporal coordination of the hip and knee joints during the flight phase of a saut de chat leap, where dancers aim to achieve a split position in the air when the center of mass (COM) reaches peak height. METHODS: Thirty healthy, experienced dancers with 22.5±4.5 years of dance training performed 5 saut de chat leaps. The timing of peak hip and knee joint angles and velocities for the takeoff and leading legs were extracted and compared to the time when COM reached peak height in the leap using a repeated measures ANOVA, with post-hoc comparisons made using paired t-tests. RESULTS: Dancers demonstrated significant differences in timing associated with achieving the split position (main effect p<0.001), with only peak leading leg hip flexion occurring at a similar time to the COM reaching peak height (paired t-test p=0.074). CONCLUSIONS: The results of this study provide insight into coordination patterns used by trained dancers. Trained dancers demonstrate patterns in timing that may be important for successful performance. The hip and knee coordination patterns during flight demonstrate how dancers work to achieve the desired aesthetics of a saut de chat leap. However, it appears that dancers do not reach the full split position at the height of the leap, as would be aesthetically desirable.

Interlimb Force Coordination in Bipedal Dance Jumps: Comparison Between Experts and Novices.

Bipedal tasks require interlimb coordination that improves with practice and acquisition of skills. The purpose of this study was to compare interlimb force coordination during dance-specific rate-controlled consecutive bipedal jumps (sautés) between expert dancers and nondancers. To analyze coordination of vertical ground reaction forces recorded under each leg, the vector coding approach was used. Although there were no differences in the patterns of interlimb force coordination between groups, the dancers exhibited less variability of interlimb force coordination during the transition phase from weight acceptance to propulsion as well as during the propulsion phase itself. The interlimb force coordination variability was associated with task performance only during the transition phase, which highlights the potential importance of control during this phase. In conclusion, expert dancers were better at reducing interlimb force coordination variability during the task-relevant transition phase, which was related to better performance at maintaining jump rate and jump height consistency.

Heeled Shoes Increase Knee Work Demand During Repeated Hopping in Dancers.

AIMS: Dancers have high injury rates of the lower extremity. External factors such as footwear likely alter the work demands placed on the lower extremity joints when performing dance-style movements. Research on pedestrians shows an increase in knee work demand when wearing heels, which may occur in dancers as well. The purpose of this study was to assess the effect of heeled shoes on lower extremity joint work demand during a basic dance-specific jump (sauté) in dancers when compared to barefoot. METHODS: Ten healthy, female dancers (age 25.6±4.7 yrs; height 1.7±0.1 m; weight 64.9±9.2 kg; mean years of dance training 17.6±6.4) performed repetitive vertical bipedal dance jumps (sautés) barefoot as well as wearing heeled dance shoes. Sagittal plane hip, knee, and ankle kinetics were calculated. Percentages of work done by these joints were calculated in comparison to the work done by the leg as a whole and compared between the two conditions. RESULTS: During a dance-specific jump, the percent contribution of energy absorption was significantly different at the ankle and knee between the two conditions. The ankle contribution decreased from 50.7±6.1% in the bare condition to 34.9±5.3% in the shod condition (p=0.002), and the knee contribution increased from 38.6±3.9% barefoot to 55.1±2.8% shod (p=0.002). The same pattern was seen for energy generation, with the ankle contribution decreasing from 48.1±7.3% to 35.6±6.9% and the knee contribution increasing from 43.3±5.6% to 56.4±6.1% in the bare vs shod condition (both p=0.002). There was no significant difference in the percent contribution from the hip. CONCLUSION: With heeled shoes, there is a shift in work demand from the ankle to the knee with no change at the hip as compared to barefoot.

Kinematic and kinetic analyses of the toes in dance movements.

Due to the significant amount of time dancers spend on the forefoot, loads on the metatarsophalangeal joints are likely high, yet vary between dance movements. The purpose of this study was to compare joint motion and net joint moments at the metatarsophalangeal joints during three different dance movements ranging in demands at the foot and ankle joints. Ten healthy, female dancers (27.6 ± 3.2 years; 56.3 ± 6.9 kg; 1.6 ± 0.1 m) with an average 21.7 ± 4.9 years of dance training performed relevés (rising up onto the toes), sautés (vertical bipedal jumps), and saut de chat leaps (split jumps involving both vertical and horizontal components). Metatarsophalangeal joint kinematics and kinetics in the sagittal plane were calculated. Total excursion and peak net joint moments during rising or push-off were compared between the three dance movements. Greater extension of the metatarsophalangeal joints was seen during relevés compared to sautés or saut de chat leaps, and the largest metatarsophalangeal net joint moments were seen during saut de chat leaps. The metatarsophalangeal joints frequently and repetitively manage external loads and substantial metatarsophalangeal extension during these three dance movements, which may contribute to the high rate of foot and ankle injuries in dancers.

Lower Extremity Biomechanical Demands During Saut de Chat Leaps.

In dance, high demands are placed on the lower extremity joints during jumping tasks. The purpose of this study was to compare biomechanical demands placed on the lower extremity joints during the takeoff and landing phases of saut de chat leaps. METHODS: Thirty healthy, experienced dancers with 20.8±4.9 yrs of dance training performed 5 saut de chat leaps. A three-dimensional motion analysis system and force plates were used to collect kinematic and kinetic data. Ground reaction force (GRF) peaks and impulse and sagittal plane kinematics and kinetics of the hip, knee, ankle, and metatarsophalangeal (MTP) joints were calculated for the takeoff and landing phases of each leap. RESULTS: Saut de chat takeoffs demonstrated greater braking GRF impulse (p<0.001), while landings demonstrated greater peak vertical GRF (p<0.001). During takeoff, greater kinetic demands were placed on the MTP (p<0.001) and ankle (p<0.001) joints, while during landing greater kinetic demands were placed on the hip (p=0.037) joint. CONCLUSIONS: Both the takeoff and landing phases of saut de chat leaps place significant demands on a dancer's body. Takeoff involves greater demands on the more distal joints and requires more braking forces, while the landing phase involves greater demands on the more proximal joints of the lower extremity and requires the dancer to absorb more vertical force. These demands, combined with extensive repetition of movements during training, may contribute to the high number of chronic injuries seen in dance.

The neuromechanical adaptations to Achilles tendinosis.

KEY POINTS: Achilles tendinosis is a localized degenerative musculoskeletal disorder that develops over a long period of time and leads to a compliant human Achilles tendon. We demonstrate that the compliant Achilles tendon elicited a series of adaptations from different levels of the human movement control system, such as the muscle-tendon interaction, CNS control and other muscles in the lower leg. These results illustrate the human body's capacity to adapt to tendon pathology and provide the physiological basis for intervention or prevention strategies. Human movement is initiated, controlled and executed in a hierarchical system including the nervous system, muscle and tendon. If a component in the loop loses its integrity, the entire system has to adapt to that deficiency. Achilles tendon, when degenerated, exhibits lower stiffness. This local mechanical deficit may be compensated for by an alteration of motor commands from the CNS. These modulations in motor commands from the CNS may lead to altered activation of the agonist, synergist and antagonist muscles. The present study aimed to investigate the effect of tendon degeneration on its mechanical properties, the neuromechanical behaviour of the surrounding musculature and the existence of the CNS modulation accompanying tendinosis. We hypothesize that the degenerated tendon will lead to diminished tissue mechanical properties and protective muscle activation patterns, as well as an up-regulated descending drive from the CNS. Strong evidence, as reported in the present study, indicates that tendinotic tendons are more compliant compared to healthy tendons. This unilateral involvement affected the neuromuscular control on the involved side but not the non-involved side. The muscle-tendon unit on the tendinotic side exhibits a lowered temporal efficiency, which leads to altered CNS control. The altered CNS control is then expressed as an adapted muscle activation pattern in the lower leg. Taken together, the findings of the present study illustrate the co-ordinated multi-level adaptations to a mechanical lesion in a tendon caused by pathology.

Pointing the foot without sickling: an examination of ankle movement during jumping.

The sauté is a relatively simple dance jump that can be performed by both highly skilled dancers and non-dancers. However, there are characteristics of jumping unique to trained dancers, especially in terms of foot and ankle movement during flight. Dancers are trained not to "sickle, " or to avoid the anatomically coupled ankle inversion that occurs with plantar flexion, maintaining the appearance of a straight line through the lower leg and foot. The purpose of this study was to examine ankle movements in elite dancers compared to non-dancers. Twenty healthy females, 10 with no prior dance training and 10 professional dancers, performed 20 consecutive sautés while three-dimensional kinematic data were collected. Sagittal and frontal plane kinematics were calculated and vector coding methods were used to quantify coordination patterns within the ankle in the sagittal and frontal planes. This pattern was chosen for analysis to identify the avoidance of a sickled foot by trained dancers. Peak ankle positions and coordination patterns between groups were examined using independent t-tests (a <0.05). Dancers demonstrated greater peak plantar flexion (p<0.01) and less change in ankle angle during the flight phase (p= 0.01), signifying holding the pointed foot position during flight. There was no statistically significant difference in sagittal and frontal plane ankle coupling (p= 0.15); however, the Cohen's d effect size for the difference in coupling was medium-to-large (0.73). Dynamic analysis of the foot and ankle during jumping demonstrates how elite dancers achieve the aesthetic requirements of dance technique.

Toe Flexor Strength, Flexibility and Function and Flexor Hallucis Longus Tendon Morphology in Dancers and Non-Dancers.

Tendinopathy of the flexor hallucis longus (FHL), colloquially referred to as "dancer's tendinitis," is a common condition in dancers and attributed to high demand on this muscle in positions of extreme ankle plantarflexion and metatarsophalangeal (MTP)) flexion and extension. Despite such a high prevalence, there has been little research into preventative or nonsurgical interventions. As a means to identify potential targets for prevention and intervention, this study aimed to characterize toe flexors in dancers by measuring strength, flexibility, function, and FHL tendon morphology. Dancers (n=25) were compared to non-dancers (n=25) in toe flexor isometric strength, first MTP joint range of motion, foot longitudinal arch flexibility, balance ability, endurance during modified heel raises without use of the toes, and FHL tendon thickness, cross-sectional area, and peak spatial frequency. Significant differences were found in functional first MTP joint extension (dancers 101.95°, non-dancers 91.15°, p<0.001), balance ability during single-leg stance on the toes (dancers 11.43 s, non-dancers 5.90 s, p=0.013), and during modified heel raises (dancers 22.20 reps, non-dancers 28.80 reps, p=0.001). Findings indicate that dancers rely on toe flexors more than non-dancers to complete balance and heel raise tasks. Efficacy of using this modified heel raise task with the toes off the edge of a block as a means to train larger plantarflexors and as a nonsurgical intervention should be studied in the future. Improving interventions for FHL tendinopathy will be impactful for dancers, in whom this condition is highly prevalent.

Exploring Active and Passive Contributors to Turnout in Dancers and Non-Dancers.

OBJECTIVE: Lower-extremity external rotation, or turnout, is a fundamental skill in dance. Active standing turnout has previously been measured using low-friction turnout disks. Turnout is influenced by passive range of motion (ROM) and strength, with passive ROM a function of bony morphology and ligamentous/capsular restraints. PURPOSE: Our study explored the relationship between standing active turnout and femoral bony morphology, hip passive ROM, and strength among dancers and non-dancers. METHODS: Cross-sectional cohort study. Twenty-three female dancers and 13 female non-dancers aged 18 to 30 yrs were recruited. Standing active turnout on reduced-friction disks, ultrasound images of femoral version, supine passive turnout, and hip abductor and external rotator strength were collected. RESULTS: Dancers demonstrated greater standing turnout (107° ± 18°) than non-dancers (92° ± 28°), but the difference was not statistically significant (p=0.054). A significant difference was found for femoral version (p<0.001), 4.7° ( ± 2.8°) for dancers vs 12.1° ( ± 4.6°) for non-dancers. Dancers demonstrated greater supine turnout, 102.7°±18.8°, compared to non-dancers, 84.3° ± 30.4° (p=0.031). Dancers were able to achieve greater peak force in turnout compared to non-dancers: 2.44 ± 0.44 N/kg and 1.72 ± 0.59 N/kg, respectively (p<0.0001). Supine total turnout was the best predictor of active turnout, contributing 48% of the variance (r=0.696, p<0.001). CONCLUSION: Our findings suggest supine turnout is the largest predictor for standing turnout. Investigating dancers and non-dancers independently, our finding were similar to previous studies suggesting the femoro-acetabular complex may be influenced by dance training, contributing to differences in bony morphology between dancers and non-dancers. Although strength did not significantly contribute to active standing turnout, dancers demonstrated greater peak force compared to non-dancers.

Intensive, progressive exercise improves quality of life following lumbar microdiskectomy: a randomized controlled trial.

OBJECTIVE: The purpose of the study was to examine changes in quality of life measures in patients who have undergone an intensive exercise program following a single level microdiskectomy. DESIGN: Randomized controlled trial with blinded examiners. SETTING: The study was conducted in outpatient physical therapy clinics. SUBJECTS: Ninety-eight participants (53 male, 45 female) who had undergone a single-level lumbar microdiskectomy allocated to receive exercise and education or education only. INTERVENTIONS: A 12-week periodized exercise program of lumbar extensor strength and endurance training, and mat and upright therapeutic exercises was administered. OUTCOME MEASURES: Quality of life was tested with the Short Form 36 (SF-36). Measurements were taken 4-6 weeks postsurgery and following completion of the 12-week intervention program. Since some participants selected physical therapy apart from the study, analyses were performed for both an as-randomized (two-group) design and an as-treated (three-group) design. RESULTS: In the two-group analyses, exercise and education resulted in a greater increase in SF-36 scales, role physical (17.8 vs. 12.1) and bodily pain (13.4 vs. 8.4), and the physical component summary (13.2 vs. 8.9). In the three-group analyses, post-hoc comparisons showed exercise and education resulted in a greater increase in the SF-36 scales, physical function (10.4 vs. 5.6) and bodily pain (13.7 vs. 8.2), and the physical component summary (13.7 vs. 8.9) when compared with usual physical therapy. CONCLUSIONS: An intensive, progressive exercise program combined with education increases quality of life in patients who have recently undergone lumbar microdiskectomy.

Trunk coordination in dancers and nondancers.

Variability, or how a task changes across trials, may reveal differences between athletes of differing skill levels. The purpose of this study was to examine trunk and lower extremity (LE) single joint kinematic variability and intersegmental coordination variability in dancers and nondancers during bipedal vertical dance jumps (sautés). Twenty healthy females, 10 with no formal dance training and 10 professional dancers, performed 20 consecutive sautés. Single joint kinematic variability was assessed using mean standard deviation of angular displacement, and intersegmental coordination variability was assessed using angular deviation of the coupling angle between segments. Within the context of the standard error of measure, there was no difference in single joint kinematic variability between dancers and nondancers. Intersegmental coordination variability in the trunk was higher than variability in LE couplings for both groups. Dancers had lower intersegmental coordination variability than nondancers for LE sagittal, frontal, and transverse plane couplings, and sagittal plane trunk couplings. Trunk adjustments may be important for successful performance, but lower intersegmental coordination variability in expert dancers indicates a higher level of control. Trunk coordination and postural control may be important factors to investigate in skilled athletes.

Achilles and patellar tendon morphology in dancers with and without tendon pain.

OBJECTIVES: To examine Achilles and patellar tendon morphology in dancers with and without tendon pain. METHODS: Fifty-three dancers with and without Achilles and/or patellar tendon pain participated. Eleven age-matched non-dancers served as controls. Longitudinal ultrasound images of the middle and distal Achilles and proximal and distal patellar tendons were acquired. To assess macromorphology, the thickness of the middle and distal Achilles and proximal and distal patellar tendons were measured. Micromorphology was analyzed by selecting 2 x 2-mm2 regions of interest in the tendons; spectral analysis using the fast Fourier transform was run for several kernels (2 x 2-mm2 subimages) within each image, and the peak spatial frequency (PSF) was extracted. A one-way ANOVA compared asymptomatic, symptomatic, and control tendon thickness and PSF. RESULTS: Macromorphology: There was no significant difference between asymptomatic and symptomatic dancers in middle or distal Achilles tendon thickness and distal patellar tendon thickness. Proximal patellar tendons in control subjects were thinner than those in asymptomatic (p=0.036) and symptomatic (p=0.003) dancers. Micromorphology: There was no significant difference in PSF between asymptomatic and symptomatic dancers and controls in the Achilles or patellar tendon. CONCLUSION: Increased proximal patellar tendon thickness without changes in tendon micromorphology suggests that tendon adaptations are more likely activity-related and less likely influenced by degeneration.

Flexor hallucis longus tendon morphology in dancers clinically diagnosed with tendinopathy.

PURPOSE: The unique demands of dance technique make dancers more prone to certain pathologies especially of the foot and ankle. Flexor hallucis longus (FHL) tendinopathy, colloquially known as "dancer's tendinopathy," is common in dancers and not well studied. The purpose of this study was to assess if morphological alterations in tendon structure occur as an adaptive response to dance activity by comparing the FHL tendon in dancers to non-dancers, and if pathology further alters tendon morphology in dancers clinically diagnosed with tendinopathy. METHODS: Three groups of ten participants were recruited (healthy non-dancers, healthy dancers, and dancers with FHL tendinopathy). Ultrasound images of the FHL tendons were analyzed for macromorphology by measuring the tendon thickness. The micromorphology was analyzed by determining the peak spatial frequency radius of the tendon. Our study did find increased tendon proper and composite tendon thickness in dancers with tendinopathy but no difference between asymptomatic dancers and non-dancers. RESULTS: There was no significant difference in micromorphology found between any of the groups. As expected, dancers with tendinopathy demonstrated increased composite tendon and tendon proper thickness however, there was no evidence of adaptive thickening of the FHL tendon as might be expected for the dance population. There was also no evidence of micromorphological changes in the presence of clinically diagnosed FHL tendinopathy. CONCLUSION: Because of the limited normative data for this pathology, these results can help improve diagnosis and therefore treatment for dancers to decrease the impact of this injury on their careers.

Resistance Exercise Program Is Feasible and Effective in Improving Functional Strength in Post-COVID Survivors.

Background: Evidence suggests that COVID-19 infection can cause lasting health consequences. Multidisciplinary rehabilitation services have been recommended to reduce the sequalae. However, the effectiveness of physical exercise interventions remains insufficiently documented. The aim of this study was to develop and implement a specific and well-tolerated protocol-based intervention to reduce muscle weakness in older adults impacted by COVID-19. Methods: Forty-six older adults were randomized into intervention and control groups. Isometric and isokinetic strength assessments were conducted for selected muscle groups using a JBA Staniak® torquemeter and Biodex System 3 dynamometer. Functional abilities were evaluated with the Time Up and Go test and Chair Stand Tests. Results: Men in the intervention group demonstrated a significant improvement in static conditions for knee flexors (KFs), trunk extensors (TEs) and trunk flexors (TFs) and in dynamic conditions for knee extensors (KEs). Women in the intervention group showed a significant improvement in static conditions for EFs, KFs, TEs and TFs and in dynamic conditions for a KE and a KF. The interaction GROUP × TESTING SESSION was significant for the Chair Test (s) and Chair Test (n). Conclusions: Our results demonstrate the effectiveness of a well-tolerated, protocol-based approach that can be used to diminish long-lasting functional deficits in post-COVID survivors.