Physical ability, cervical function, and walking plantar pressure in frail and pre-frail older adults: An attentional focus approach.

Aging and increased vulnerability define the clinical condition of frailty. However, while the cervical function is recognized as a determinant of balance and walking performance, no study simultaneously physical ability, cervical function, balance, and plantar pressure distribution in walking in nursing house population. Thus, the present study aimed to compare these parameters between Frail and Pre-Frail aged people. Thirty-one (12 men and 19 women) institutionalized participants (age: 89.45 ± 5.27 years, weight: 61.54 ± 9.99 kg, height: 160.34 ± 7.93 cm) were recruited and divided into Pre-Frail and Frail groups according to SPPB (Short Physical Performance Battery) score (Frail <6, Pre-Frail ≥6). Participants performed the Timed Up and Go Test (TUGT) and a static balance evaluation. The cervical range of motion (COM), knee extensor strength, and walking plantar pressure distribution have been measured. The Pre-Frail group showed a higher gait speed (ES = 0.78, p ≤ 0.001) and a better TUGT, as well as higher knee extensor strength (ES = 0.4, p = 0.04). Furthermore, the Pre-Frail group presented a center of pressure (COP) displacement velocity on the sagittal axis (ES = 0.43, p = 0.02) and a more COP projection on this axis (ES = 0.43, p = 0.02). No significant difference has been observed between the two groups concerning the total contact time and most of the plantar pressure parameters except for the rear foot relative contact time which was lower in the Pre-Frail group. The Pre-Frail group also showed better cervical tilt mobility (ES = 0.35, p = 0.04). This study highlights the influence of some new parameters on frailty in older people, such as cervical mobility and plantar pressure distribution in walking.

The short-term effect of a myofascial protocol versus light touch applied to the cervical spine towards the prevention of balance disorders in the elderly: protocol of a randomised controlled trial.

BACKGROUND: Falling is a major trauma that can occur with aging, leading to very significant psychological and physical health effects with financial and societal consequences. It is therefore essential to explore therapeutic treatments that can reduce this risk. Some recognized effective treatments exist, concerning in particular the re-education of the muscles of the lower limbs. However, to our knowledge, none of them focus on the cervical spine although the latter is located at an essential physiological crossroads. Manual therapy, which has already demonstrated its impact on pain and balance parameters in the elderly, could be a painless and non-invasive tool of choice in addressing this problem. METHODS: Interventional study (not related to a health product), monocentric, prospective, controlled, randomized double-blind (patient and evaluator performing the measurements). The experiment will take place over three measurement periods on D0, D7 and D21. On D0 subjects will be randomized in 2 groups: experimental and placebo group. Both groups will be assessed on: Short Physical Performance Battery test score, walking speed, lower limb strength, balance, heart rate variability and cervical spine strength and mobility. Then the experimental group will receive a myofascial release protocol applied to the cervical spine and the placebo group will receive a placebo light touch protocol. The intervention will be followed by the same measurements as before. This schedule will be reproduced on D7. On D21, only one assessment will be done. DISCUSSION: This study started in 2020 but could not go beyond the inclusion phase due to the COVID pandemic. It is envisaged that recruitment could resume during 2022. TRIAL REGISTRATION: Registered by the Comité de Protection des Personnes-Sud Méditerranée; under the title "Prévention des troubles de l'équilibre chez le senior: influence de la thérapie manuelle appliquée au rachis sur les paramètres statiques et dynamiques¼, n° 19.12.27.47.259 in date of February 4, 2020. Registered by ClinicalTrials.gov ID: NCT05475652; under the title « The Influence of Manual Therapy Applied to the Cervical Spine in the Prevention of Balance Disorders in the Elderly (ManEq)".

Age-related differences of inter-joint coordination in elderly during squat jumping.

BACKGROUND: Explosive movement requires that the individual exerts force and power with appropriate magnitude and timing. These coordination aspects have received less attention despite being a basic prerequisite for daily mobility and physical autonomy, especially in older people. Therefore, the purpose of this study is to characterize the effect of age on inter-joint coordination during explosive movement. METHODS: Twenty-one elderly and twenty young participants performed three maximal vertical jumps, while kinematics were recorded throughout each squat jump. Inter-joint coordination and coordination variability were calculated for selected sagittal hip-knee, knee-ankle, and hip-ankle joint couplings using the continuous relative phase method. RESULTS: The young participants produced significantly greater jump height performance (0.36 ± 0.07 m vs. 0.12 ± 0.04 m, p < 0.001). The mean absolute continuous relative phase for ankle-knee and knee-hip joint couplings were significantly greater for the elderly in comparison to the young group (p < 0.01 for the both). No significant differences between senior and young participants in the mean absolute continuous relative phase for ankle-hip joint couplings (p = 0.25) was observed. However, there was significantly more variability in inter-joint coordination in the elderly marked by greater continuous relative phase variabilities in ankle-knee, ankle-hip and knee-hip joint couplings (p < 0.001) than those observed in young adults. CONCLUSION: In this study, seniors demonstrated proximodistal inter-joint coordination but with different delays in the pattern of inter-joint coordination during squat jumps compared to young adults. In addition, a higher continuous relative phase variability in the elderly may be needed to improve stability or compensate for strength deficits in jump achievement.

Explosive movement in the older men: analysis and comparative study of vertical jump.

BACKGROUND: Loss of power has been demonstrated to have severe functional consequences to perform physical daily living tasks in old age. PURPOSE: This study aimed to assess how moment and velocity were affected for each joint of the lower limbs during squat jumping for older men in comparison with young adults. METHODS: Twenty-one healthy older men (74.5 ± 4.6 years) and 22 young men (21.8 ± 2.8 years) performed maximal squat jumps. Inverse dynamics procedure was used to compute the net joint power, moment and velocity produced at the hip, knee and ankle joints. RESULTS AND DISCUSSION: Vertical jump height of the elderly was 64 % lower than the young adults. The maximal power of the body mass center (P maxbmc ) was 57 % lower in the older population. For the instant at P maxbmc , the vertical ground reaction force and the vertical velocity of the body mass center were 26 % and 35 % less in the older adults than in the young adults, respectively (p < 0.05; ES = -1.64 for vertical ground reaction force; p < 0.05; ES = -1.10). A lower value of the hip (-60 %), knee (-72 %) and ankle (-68 %) joint powers was observed in older adults. This was explained by both lower values of joint moments (-64, -57 and -61 % for the hip, knee and ankle, respectively) and angular velocities (-59, -49 and -52 % for the hip, knee and ankle, respectively). CONCLUSION: This study showed a lower joint power when performing vertical jump. This smaller power resulted from both a lower moment and angular velocity produced at each joint.

Asymmetry of Inter-joint Coordination during Single Leg Jump after Anterior Cruciate Ligament Reconstruction.

Little is known about the contralateral asymmetry in inter-joint coordination after anterior cruciate ligament reconstruction (ACL-R) during multi-segmental movements. This study aimed to evaluate inter-joint coordination asymmetry between the injured (IL) and non-injured leg (NIL) in patients after ACL-R during single-leg jumping. 12 male patients having undergone ACL-R (7.3 months post-surgery) and 12 healthy males performed maximal vertical single-leg jumps with the right and left leg. The kinematics of each jump were recorded. The inter-joint coordination between the ankle, knee and hip joints was assessed by computing the continuous relative phase (CRP) and its variability. The effect of the group and leg was tested with a mixed linear model. The CRP and its variability were similar between the dominant and non-dominant leg of the healthy group. By contrast the CRP of the coupling ankle/knee and ankle/hip was smaller (p<0.01) for IL in comparison to NIL in the ACL-R group (-30% and -22% respectively). The CRP variability of the couplings ankle/knee and knee/hip was greater (p<0.05) for IL compared to NIL (+23% and +40% respectively). In conclusion, the jumping strategy assessed through the analysis of inter-joint coordination was still affected in ACL-R patients, which may be a cause of re-injury.

Contralateral limb deficit seven months after ACL-reconstruction: an analysis of single-leg hop tests.

BACKGROUND: Following ACL-reconstruction, the non-injured leg (NIL) is used as a reference to assess injured leg (IL) recovery. However, deficits have been reported in the NIL questioning its use as a reference. The aim of this study is to assess whether NIL deficits are present while jumping after ACL-reconstruction. METHODS: Thirteen males who had undergone ACL-reconstruction and 16 healthy subjects took part in the experiment. Jumping performance was assessed during a single and a triple hop for distance. Jumping performance, kinematic and kinetic data were recorded during single leg squat jumps. Values for both the NIL and the IL were compared to those of a control group (CG). RESULTS: Jumping performance for single and triple hop for distance and single leg squat jump was lower in the NIL than in the CG (p=0.004, p=0.002, and p=0.016, respectively). During the squat jump, the knee joint was more extended and the ankle plantar-flexion was greater at take-off while the peak total moment was 15% lower in the NIL than in the CG (p=0.002, p=0.002, and p=0.009, respectively). We found consistent evolutions in the NIL and the IL compared to the CG for jumping performance, initial joint angles, and peak total moment during the squat jump, but the opposite was found for the ankle and knee joint angles at squat jump take-off. CONCLUSIONS: Jumping strategies are impaired in the NIL after ACL-R during jump tasks with some deficits matching those observed in the IL and some specific to the NIL. LEVEL OF EVIDENCE: III, Case control study.

Effects of spine flexion and erector spinae maximal force on vertical squat jump height: a computational simulation study.

The purpose of this study was to evaluate the single and combined effects of initial spine flexion and maximal isometric force of the erector spinae on maximal vertical jump height during maximal squat jumping. Seven initial flexions of the 'thorax-head-arm' segment (between 20.1° and 71.6°) and five maximal isometric forces of the erector spinae (between 5600 and 8600 N) were tested. Thus, 35 squat jumps were simulated using a 2D simulation model of the musculoskeletal system. Vertical jump height varied at most about 0.094 and 0.021 m when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. These results were explained for the most part by the variation of total muscle work. The latter was mainly influenced by the work produced by the erector spinae which increased at most about 57 and 110 J when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. It was concluded that the increase in the initial flexion of the 'thorax-head-arm' segment and in the maximal isometric force of the erector spinae enables an increase in maximal vertical jump height during maximal squat jumping.

Motion alterations after anterior cruciate ligament reconstruction: comparison of the injured and uninjured lower limbs during a single-legged jump.

CONTEXT: Asymmetries subsist after anterior cruciate ligament reconstruction (ACL-R), and it is unclear how lower limb motion is altered in the context of a dynamic movement. OBJECTIVE: To highlight the alterations observed in the injured limb (IL) during the performance of a dynamic movement after ACL-R. DESIGN: Cross-sectional study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 11 men (age = 23.3 ± 3.8 years, mass = 81.2 ± 17.0 kg) who underwent ACL-R took part in this study 7.3 ± 1.1 months (range = 6-9 months) after surgery. INTERVENTION(S): Kinematic and kinetic analyses of a single-legged squat jump were performed. The uninjured leg (UL) was used as the control variable. MAIN OUTCOME MEASURE(S): Kinematic and kinetic variables. RESULTS: Jump height was 24% less for the IL than the UL (F1,9 = 23.3, P = .001), whereas the push-off phase duration was similar for both lower limbs (P = .96). Knee-joint extension (F1,9 = 11.4, P = .009), and ankle plantar flexion (F1,9 = 22.6, P = .001) were less at takeoff for the IL than the UL. The hip angle at takeoff was not different between lower limbs (P = .09). We found that total moment was 14% less (F1,9 = 11.1, P = .01) and total power was 35% less (F1,9 = 24.2, P = .001) for the IL than the UL. Maximal hip (P = .09) and knee (P = .21) power was not different between legs. The IL had 34% less maximal ankle power (F1,9 = 11.3, P = .009) and 31% less angular velocity of ankle plantar flexion (F1,9 = 17.8, P = .004) than the UL. CONCLUSIONS: At 7.3 months after ACL-R, motion alterations were present in the IL, leading to a decrease in dynamic movement performance. Enhancing the tools for assessing articular and muscular variables during a multijoint movement would help to individualize rehabilitation protocols after ACL-R.

Influence of lumbar spine extension on vertical jump height during maximal squat jumping.

The purpose of this study was to determine the influence of lumbar spine extension and erector spinae muscle activation on vertical jump height during maximal squat jumping. Eight male athletes performed maximal squat jumps. Electromyograms of the erector spinae were recorded during these jumps. A simulation model of the musculoskeletal system was used to simulate maximal squat jumping with and without spine extension. The effect on vertical jump height of changing erector spinae strength was also tested through the simulated jumps. Concerning the participant jumps, the kinematics indicated a spine extension and erector spinae activation. Concerning the simulated jumps, vertical jump height was about 5.4 cm lower during squat jump without trunk extension compared to squat jump. These results were explained by greater total muscle work during squat jump, more especially by the erector spinae work (+119.5 J). The erector spinae may contribute to spine extension during maximal squat jumping. The simulated jumps confirmed this hypothesis showing that vertical jumping was decreased if this muscle was not taken into consideration in the model. Therefore it is concluded that the erector spinae should be considered as a trunk extensor, which enables to enhance total muscle work and consequently vertical jump height.

Movement in a gravitational field: The question of limb interarticular coordination in terrestrial vertebrates.

In this paper, we demonstrated that interarticular coordination of terrestrial tetrapods emerges from an environment highly constrained by friction and the gravitational field. We briefly review recent works on the jumping behavior in squamates, lemurs and amphibians. We then explore previously published work as well as some unpublished experimental data on human jumping. Finally, we end by inferring locomotion in some of the first limbed vertebrates using a simulation procedure. All these data show that despite changes in shape, structure, and motor controls of taxa, the same spatio-temporal sequence of joint displacements always occurs when the movement is executed in a terrestrial environment. Comparison with aquatic locomotion argues for the hypothesis that this pattern emerged in early terrestrial tetrapods as a response to the gravitational constraint and the terrestrial frictional environment.

Measurement of pelvic motion is a prerequisite for accurate estimation of hip joint work in maximum height squat jumping.

In experiments investigating vertical squat jumping, the HAT segment is typically defined as a line drawn from the hip to some point proximally on the upper body (eg, the neck, the acromion), and the hip joint as the angle between this line and the upper legs (θUL-HAT). In reality, the hip joint is the angle between the pelvis and the upper legs (θUL-pelvis). This study aimed to estimate to what extent hip joint definition affects hip joint work in maximal squat jumping. Moreover, the initial pelvic tilt was manipulated to maximize the difference in hip joint work as a function of hip joint definition. Twenty-two male athletes performed maximum effort squat jumps in three different initial pelvic tilt conditions: backward (pelvisB), neutral (pelvisN), and forward (pelvisF). Hip joint work was calculated by integrating the hip net joint torque with respect to θUL-HAT (WUL-HAT) or with respect to θUL-pelvis (WUL-pelvis). θUL-HAT was greater than θUL-pelvis in all conditions. WUL-HAT overestimated WULpelvis by 33%, 39%, and 49% in conditions pelvisF, pelvisN, and pelvisB, respectively. It was concluded that θUL-pelvis should be measured when the mechanical output of hip extensor muscles is estimated.

Submaximal leaping in the grey mouse lemur.

In arboreal animals such as the grey mouse lemur (Microcebus murinus Miller, 1777), leaping is the most frequent strategy for predator avoidance. The aim of this study was to characterise the locomotor adaptation in response to the structural constraint of the habitat (i.e., position of the landing substrate). Thus, we characterised the push-off phase by inducing the lemurs to leap up to a range of heights from horizontal to their own individual highest performance. Using uniplanar high-frequency cineradiographs collected in a sagittal plane, the relative contributions of the centre of mass (CoM) velocity vector magnitude and orientation to leaping performance were evaluated. The kinematics of the push-off phase showed that for low landing heights, leaping performance was essentially due to hip and knee extensions. Higher leaps seemed to be related to an increase in ankle contribution. At all leaping heights, the proximal-to-distal sequence of the hind limb joints controlled the orientation and magnitude of the M. murinus CoM velocity vector while pushing off. Finally, the analysis of the velocity vector at the onset of take-off suggested that the optimal solution for predator avoidance was to leap for horizontal distance and not for vertical distance.

Hindlimb interarticular coordinations in Microcebus murinus in maximal leaping.

The purpose of this study was to investigate the pattern of coordinations of the hindlimb joints in the world's smallest living primate (Microcebus murinus). The sequencing and timing of joint rotations have been analyzed in five adult males performing maximal leaping from a take-off immobile platform to their own wooden nest. Angular kinematics of hip, knee, angle and metatarso-phalangeal (MT) joints were deduced from high-speed X-ray films in the sagittal plane of the animals. The body mass center (BMC) of the lemurs was assimilated to their iliac crest. The maximal airborne performance of the lemurs was 0.33+/-0.04 m, which represented 2.55+/-0.36 times their snout-vent length. Take-off instant occurred 72+/-7 ms after the start of the push-off, with a BMC velocity of 3.23+/-0.48 m s(-1), oriented 55+/-14 deg. with the horizontal plane. The kinematic analysis of the joints and musculo-tendon architecture of the M. murinus plantar flexors pointed out mechanical power amplifier mechanisms (i.e. stretch-shortening cycle of hindlimb muscles and proximo-to-distal sequence).

Influence of swimsuit design and fabric surface properties on the butterfly kinematics.

This study investigated the influence of the covering swimsuit and the fabric surface properties on the butterfly stroke kinematics. Surface properties were evaluated by wetting measurements of two fabric samples: one for training suits and one for competition suits. The surface of the second one was coated by mechanochemical treatment in order to modify its surface properties. Nine national level swimmers performed a 50-m butterfly at submaximal velocity in three swimsuit conditions: conventional, long, and coated long swimsuits. From video recording, the hip was digitized at the entry and exit of the swimmer's hand in order to calculate the duration, hip displacement, and hip linear velocity during underwater and recovery phases and during stroke. The results for wetting show that competition fabric was more water-repellent than training fabric, but both were isotropic. Moreover, the mechanochemical treatment increased water repellency and anisotropy. The swimming results indicated that, when compared to a conventional swimsuit, wearing a coated long swimsuit increased hip linear velocity during stroke, and particularly during the recovery phase which had a shorter duration. These results suggest that the covering swimsuit should be coupled with the water repellent and anisotropic properties of the fabric surface in order to improve swimming performance.

Influence of figure skating skates on vertical jumping performance.

The purpose of this study was to investigate the influence of wearing figure skating skates on vertical jump performance and interjoint co-ordinations described in terms of sequencing and timing of joint rotations. Ten national to international figure skaters were filmed while performing a squat jump (SJ) on a force platform. Three experimental conditions were successively realized: barefoot (BF), lifting a 1.5 kg weight (LW) corresponding to the skates' mass, attached on the distal extremity of each leg and wearing skates (SK). Jump height, angular kinematics as well as joints kinetics were calculated. Relative to the SJ height reached in the BF condition, SJ performance was significantly decreased by 2.1 and 5.5 cm in the LW and SK conditions, respectively. The restriction of ankle amplitude imposed by wearing skates was found to significantly limit the knee joint amplitude while the hip angular motion was not affected. Neither the skates' mass nor the limited ankle angular motion modified the proximo-distal organization of joint co-ordination observed when jumping barefoot. However, with plantar flexion restriction, the delay between hip and knee extensions increased while it was reduced between knee and ankle extensions. Work output at the knee and ankle joints were significantly lowered when wearing skates. The decrease of work at the knee was shown to result from an early flexing moment causing a premature deceleration of the knee and from a reduction of knee amplitude. Taken together, these results show a minimization of the participation of the knee when plantar flexion is limited. It was proposed that constraining the distal joint causes a reorganization of interjoint co-ordinations and a redistribution of the energy produced by knee extensors to the hip and ankle joints.

Vertical jumping reorganization with aging: a kinematic comparison between young and elderly men.

To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18-25 years and 11 older men ages 79-100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age.

Short-term effects of using verbal instructions and demonstration at the beginning of learning a complex skill in figure skating.

This study examined whether providing verbal instructions plus demonstration and task repetition facilitates the early acquisition of a sport skill for which learners had a prior knowledge of the individual motor components. After one demonstration of the task by an expert, 18 novice skaters practiced a figure skating jump during a 15-min. period. Subjects were randomly assigned to one of 3 groups: a group provided with a verbal instruction that specified the subgoals of the task (Subgoals group), a group provided with a verbal instruction that used a metaphor (Metaphoric group), and a group not receiving any specific instruction during training (Control group). Subjects were filmed prior to and immediately following the practice session. Analysis indicated that the modifications of performance were related to the demonstration and the subsequent task repetitions only. Providing additional verbal instructions generated no effect. Therefore, guiding the learner toward a solution to the task problem by means of verbal instruction seems to be ineffective if done too early in the course of learning.