The initiation of walking

Carlsöö, S

doi:10.1159/000142864

Cited by 139 publications

(62 citation statements)

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“…This particular sequence was chosen primarily because of its quite simple EMG pattern, consisting of only two main components: inhibition of soleus EMG, followed by activation of tibialis anterior (see Carlsoo, 1966), a condition which makes it relatively straightforward to measure spatial and temporal parameters. Moreover, the reported observation of the same EMG sequence at the initiation of gait (Carlsoo, 1966), forward bending (Crenna et al 1987) and rising on tip-toes (Nardone & Schieppati, 1988) provides for the first time the opportunity of assessing the degree of synergistic relationship between components across a series of different tasks, a property which would corroborate the notion of a single programme called into action over a spectrum of various motor behaviours.…”

Section: Introductionmentioning

confidence: 99%

A motor programme for the initiation of forward‐oriented movements in humans.

Crenna

Frigo

1991

The Journal of Physiology

368

257

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SUMMARY1. The EMG sequence activated before the initiation of a number of fast forwardoriented voluntary movements was analysed quantitatively in normal subjects.2. The sequence consisted of an initial inhibitory component directed to the soleus motor nucleus, followed by a second excitatory one directed to the tibialis anterior (TA).3. The spectrum of functional utilization included motor tasks in which the prime movers are leg and thigh muscles (initiation of gait, rising on tip-toes), thigh and trunk muscles (fast-forward bending of the trunk, standing up) and upper-limb muscles (forward throw or catch).4. In a same motor task and across the different motor tasks, performed at various speeds, the latency of soleus inhibition and TA activation with respect to the onset of movement co-varied according to a linear function, indicating a close temporal correlation between the two components.5. In all the movements investigated, the earliest mechanical effect was a backward displacement of the centre of foot pressure in the sagittal plane.6. Soleus inhibition alone and TA burst alone were each able to produce a backward displacement of the centre of foot pressure, but the effect was significantly slower after soleus inhibition.7. The spatio-temporal parameters of the sequence were modulated according to the pre-existing postural conditions. For the gait initiation protocol, increasing initial forward leaning led to a decrease in the amplitude of soleus inhibition and the TA burst, and to a change in their relative time delays. Modulation was different on the two sides. We could define a postural boundary as the degree of forward leaning beyond which the full sequence is no longer called into action.8. The spatio-temporal parameters of the sequence were pre-set according to the requirements of the forthcoming movement. In the gait initiation protocol, the amplitude and synchronization of the TA burst were directly correlated with velocity of movement, while the relative delay between soleus inhibition and TA activation was inversely correlated. Modulation on the two sides differed. We could define a velocity boundary as the velocity of movement below which the full sequence is no longer called into action.9. We suggest that the EMG sequence described can be considered a motor MS 8303 P. CRENNA AND C. FRIGO programme that, through direct action on the position of the centre of foot pressure (the variable primarily controlled), will precisely adjust the configuration of forces external to the body, allowing the contraction of the prime mover(s) to interact appropriately with them for the production of a specific, forward-oriented movement.

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Section: Introductionmentioning

confidence: 99%

A motor programme for the initiation of forward‐oriented movements in humans.

Crenna

Frigo

1991

The Journal of Physiology

368

257

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“…A handful of researchers have looked into the initiation of gait, the subject of our present work, in the normal, healthy subject (1,2,6,8,12). These studies lead to a better understanding of this important period in gait and create a normal database for future work.…”

Section: Introductionmentioning

confidence: 99%

The initiation of gait in lower limb amputees: Some related data

Nissan

1991

JRRD

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Abstract-The initiation of gait, from balanced standing position to the toe-off of the stance leg, was analyzed in 8 unilateral above-knee (AK) and 10 unilateral below-knee (BK) males amputees. Thirty-one parameters were measured, including ground-foot forces and the movements and timing of hip, knee, and ankle joints. The significant changes from the normal pattern of initiation of gait found in the AK and BK amputees, as well as significant changes between the two amputees groups themselves, are described. The amputees were divided into two subgroups: those who start walking with their prosthesis and those starting with their normal leg. The two groups were compared statistically for each amputation level and all were compared to a normal subjects group. Differences relating to the choice of the swing leg were found. The findings are reported as part of a future databank.

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“…The limb that moves forward first is called the leading limb and the other limb is termed the trailing one. Able-bodied individuals activate tibialis anterior muscle and inhibit soleus activity to shift the centre of pressure (COP) posteriorly and to accelerate the centre of mass (COM) anteriorly [3][4][5][6][7][8][9]. As a result, the ground reaction force (GRF) in the anterior direction increases, thereby generating a forward momentum [3,10].…”

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confidence: 99%