Synthesis of natural arm swing motion in human bipedal walking

It has historically been believed that the role of arm motion during walking is related to balancing. Arm motion during natural walking is distinguished in that each arm swing is with the motion of the opposing leg. Although this arm swing motion is generated naturally during bipedal walking, it is interesting to note that the arm swing motion is not necessary for stable walking. This paper attempts to explain the contribution of out-of-phase arm swing in human bipedal walking. Consequently, a human motion control methodology that generates this arm swing motion during walking is proposed. The relationship between arm swing and reaction moment about the vertical axis of the foot is explained in the context of the dynamics of a multi-body articulated system. From this understanding, it is reasoned that arm swing is the result of an effort to reduce the reaction moment about the vertical axis of the foot while the torso and legs are being controlled. This idea is applied to the generation of walking motion. The arm swing motion can be generated, not by designing and tracking joint trajectories of the arms, but by limiting the allowable reaction moment at the foot and minimizing whole-body motion while controlling the lower limbs and torso to follow the designed trajectory. Simulation results, first with the constraint on the foot vertical axis moment and then without, verify the relationship between arm swing and foot reaction moment. These results also demonstrate the use of the dynamic control method in generating arm swing motion.     

Effects of step length and step frequency on lower-limb muscle function in human gait

The aim of this study was to quantify the effects of step length and step frequency on lower-limb muscle function in walking. Three-dimensional gait data were used in conjunction with musculoskeletal modeling techniques to evaluate muscle function over a range of walking speeds using prescribed combinations of step length and step frequency. The body was modeled as a 10-segment, 21-degree-of-freedom skeleton actuated by 54 muscle-tendon units. Lower-limb muscle forces were calculated using inverse dynamics and static optimization. We found that five muscles – GMAX, GMED, VAS, GAS, and SOL – dominated vertical support and forward progression independent of changes made to either step length or step frequency, and that, overall, changes in step length had a greater influence on lower-limb joint motion, net joint moments and muscle function than step frequency. Peak forces developed by the uniarticular hip and knee extensors, as well as the normalized fiber lengths at which these muscles developed their peak forces, correlated more closely with changes in step length than step frequency. Increasing step length resulted in larger contributions from the hip and knee extensors and smaller contributions from gravitational forces (limb posture) to vertical support. These results provide insight into why older people with weak hip and knee extensors walk more slowly by reducing step length rather than step frequency and also help to identify the key muscle groups that ought to be targeted in exercise programs designed to improve gait biomechanics in older adults.     

Nocturnal CPAP improves walking capacity in COPD patients with obstructive sleep apnoea

Background

Exercise limitation is an important issue in patients with chronic obstructive pulmonary disease (COPD), and it often co-exists with obstructive sleep apnoea (overlap syndrome). This study examined the effects of nocturnal continuous positive airway pressure (CPAP) treatment on walking capacity in COPD patients with or without obstructive sleep apnoea.

Methods

Forty-four stable moderate-to-severe COPD patients were recruited and completed this study. They all underwent polysomnography, CPAP titration, accommodation, and treatment with adequate pressure. The incremental shuttle walking test was used to measure walking capacity at baseline and after two nights of CPAP treatment. Urinary catecholamine and heart rate variability were measured before and after CPAP treatment.

Results

After two nights of CPAP treatment, the apnoea-hypopnoea index and oxygen desaturation index significantly improved in both overlap syndrome and COPD patients, however these changes were significantly greater in the overlap syndrome than in the COPD group. Sleep architecture and autonomic dysfunction significantly improved in the overlap syndrome group but not in the COPD group. CPAP treatment was associated with an increased walking capacity from baseline from 226.4 ± 95.3 m to 288.6 ± 94.6 m (P < 0.05), and decreased urinary catecholamine levels, pre-exercise heart rate, oxygenation, and Borg scale in the overlap syndrome group. An improvement in the apnoea-hypopnoea index was an independent factor associated with the increase in walking distance (r = 0.564).

Conclusion

Nocturnal CPAP may improve walking capacity in COPD patients with overlap syndrome.

Trial registration

{"type":"clinical-trial","attrs":{"text":"NCT00914264","term_id":"NCT00914264"}}NCT00914264     

Increasing step width reduces the requirements for subtalar joint moments and powers

The subtalar joint (STJ) contributes to the absorption and generation of mechanical energy (and power) during walking to maintain frontal plane stability. Previous observational studies have suggested that there may be a relationship between step width and STJ supination moment. This study directly tests the hypothesis that walking with a step width greater than preferred would reduce STJ moments, energy absorption, and power generation requirements, while increasing energy absorption at the hip during initial contact. Participants (n = 12, 7 females) were asked to walk on an instrumented treadmill at a constant velocity and cadence at a range of fixed step widths ranging from 0.1 to 0.4 times leg length (L). Walking at step widths greater than preferred (0.149 ± 0.04 L) reduced peak STJ moments at initial contact and propulsion which subsequently reduced the negative and positive work performed at the STJ. There was a 43% reduction in energy absorption (negative work) and approximately 30% decrease in positive work at the STJ as step width increased from 0.1 L to 0.4 L. An increase in energy absorption at the knee and hip was evident with an increase in step width during initial contact, although minimal mechanical changes were observed at the proximal joints during propulsion. These results suggest an increase in step width reduces the forces generated by muscles at the STJ across stance and is therefore likely to be beneficial in the prevention and treatment of their injuries. In terms of rehabilitation, the increase in mechanical costs occurring due to an increase in energy absorption by the hip and knee is of minimal concern.     

Association between walking ability and trunk and lower-limb muscle atrophy in institutionalized elderly women: a longitudinal pilot study

Background

The aim of this study was to investigate the association between walking ability and muscle atrophy in the trunk and lower limbs.

Methods

Subjects in this longitudinal study were 21 elderly women who resided in nursing homes. The thicknesses of the following trunk and lower-limb muscles were measured using B-mode ultrasound: rectus abdominis, external oblique, internal oblique, transversus abdominis, erector spinae, lumbar multifidus, psoas major, gluteus maximus, gluteus medius, gluteus minimus, rectus femoris, vastus lateralis, vastus intermedius, biceps femoris, gastrocnemius, soleus, and tibialis anterior. Maximum walking speed was used to represent walking ability. Maximum walking speed and muscle thickness were assessed before and after a 12-month period.

Results

Of the 17 measured muscles of the trunk and lower limbs, age-related muscle atrophy in elderly women was greatest in the erector spinae, rectus femoris, vastus lateralis, vastus intermedius, and tibialis anterior muscles. Correlation coefficient analyses showed that only the rate of thinning of the vastus lateralis was significantly associated with the rate of decline in maximum walking speed (r = 0.518, p < 0.05).

Conclusions

This longitudinal study suggests that reduced walking ability may be associated with muscle atrophy in the trunk and lower limbs, especially in the vastus lateralis muscle, among frail elderly women.     

虚拟现实平衡训练联合神经肌肉电刺激对前交叉韧带重建术后患者膝关节功能、腘绳肌肌力和步行功能的影响

摘要 目的：探讨虚拟现实平衡训练联合神经肌肉电刺激（NMES）对前交叉韧带重建术（ACLR）后患者膝关节功能、腘绳肌肌力和步行功能的影响。方法：选择2019年8月~2021年12月期间我院收治的前交叉韧带（ACL）损伤患者96例,并成功实施ACLR,采用随机数字表法分为对照组（n=48,常规康复训练、虚拟现实平衡训练）和研究组（n=48,常规康复训练、虚拟现实平衡训练联合NMES干预）。对比两组膝关节功能优良率、膝关节功能、腘绳肌肌力和步行功能。结果：研究组的临床膝关节功能优良率93.75%（45/48）高于对照组68.75%（33/48）,差异有统计学意义（P<0.05）。两组干预后膝关节功能评分、膝关节活动度对均升高,且研究组高于对照组（P<0.05）。两组干预后患侧腘绳肌等长肌力升高,且研究组高于对照组（P<0.05）,两组干预后健侧腘绳肌等长肌力对比无明显差异（P>0.05）。两组干预后步长、步速升高,且研究组高于对照组,患侧摆动相降低,且研究组低于对照组（P<0.05）。两组干预后被动活动察觉阀值、进行被动角度再生试验降低,且研究组低于对照组（P<0.05）。结论：虚拟现实平衡训练联合NMES应用于ACLR术后患者的疗效显著,有助于其膝关节功能恢复,提高腘绳肌肌力,改善步行功能。     

The influence of a 1-year programme of brisk walking on endurance fitness and body composition in previously sedentary men aged 42–59 years

This study examined the influence of a 1-year brisk walking programme on endurance fitness and the amount and distribution of body fat in a group of formerly sedentary men. Seventy-two males, aged 42–59 years, body mass index 25.2 (0.3) kg·m^–2 [mean (SEM)], were randomly allocated to either a walking group (n = 48) or control group (n = 24). Brisk walking speed was evaluated using a 1.6-km track walk. Changes in endurance fitness were assessed by measuring blood lactate concentration and heart rate during submaximal treadmill walking. Body composition was determined by hydrostatic weighing and anthropometry; energy intake was assessed from 7-day weighed food inventories. Differences in the response of walkers and controls were examined using two-way analyses of variance. Forty-two walkers (87.5%) completed the study and averaged 27.9 (1.4) min·day^–1 of brisk walking (range 11–46). Brisk walking speed averaged 1.95 (0.03) m·s^–1 and elicited approximately 68 (1) % of maximum heart rate. Heart rate and blood lactate concentration during submaximal treadmill walking were significantly reduced in the walkers after 3, 6 and 12 months and the oxygen uptake at a reference blood lactate concentration of 2 mmol·l^–1 was increased by 3.2 ml·kg^–1. min^–1 (14.9%) in the walkers at 6 months (P< 0.01). Although skinfold thicknesses at anterior thigh and medial calf sites decreased significantly for the walkers, the response of the two groups did not differ significantly for other body composition variables or for energy intake.     

Movement patterns of yellow baboons (Papio cynocephalus): Central positioning of walking infants

According to DeVore and Washburn's protection theory of the spatial organization of moving baboon troops, walking infants, which are among the most vulnerable and least self-sufficient of all troop members, should tend to occupy the troop's center. The protection theory is an ultimate hypothesis from which persistently recurring behavior is expected. Two troops living in Mikumi National Park, Tanzania, were compared with troops studied at other locations. Walking infants tended to occupy the center of their troop and to be underrepresented primarily in the frontal portion of progressions and secondarily in the rear. The lead position of progressions was analyzed using 82 walking infants, 11 troops, three locations, two species, and three studies involving eight or more observers employing somewhat different procedures at the different study sites. Despite so many opportunities for variation, 1,317 observations from these 11 troops did not produce a single instance in which a walking infant led the troop and very few in which one was in the frontal twelfth.     

三维旋进式振动疗法联合常规康复训练对脑卒中偏瘫患者上下肢痉挛状态、步行能力及生活质量的影响

摘要 目的：探讨三维旋进式振动疗法联合常规康复训练对脑卒中偏瘫患者上下肢痉挛状态、步行能力及生活质量的影响。方法：按照随机数字表法,将南京医科大学附属苏州医院2020年4月~2022年4月期间收治的80例脑卒中偏瘫患者分为对照组（常规康复训练）和实验组（三维旋进式振动疗法联合常规康复训练）,每组各40例。对比两组偏瘫侧上下肢痉挛状态、步行能力及生活质量情况。结果：两组干预4周后、干预8周后Fugl-Meyer运动功能评分（FMA）上肢、下肢评分均较干预前升高,且实验组高于对照组（P<0.05）。两组干预4周后、干预8周后步长、步速、6 min步行试验（6MWT）均较干预前升高,且实验组高于对照组（P<0.05）。两组干预8周后,生理职能（RP）、活力（VT）、生理功能（PF）、总体健康（GH）、社会功能（SF）、躯体疼痛（BP）、情感职能（RE）、精神健康（MH）均较干预前升高,且实验组高于对照组（P<0.05）。结论：三维旋进式振动疗法联合常规康复训练应用于脑卒中偏瘫患者,可有效改善上下肢痉挛状态,提高步行能力,促进生活质量提高。