Volitional Postures during Maximal Push/Pull Exertions in the Sagittal Plane

Abstract

A set of push/pull experiments was performed by six men and women of varying anthropometry who were asked to exert maximal one-handed and two-handed push and pull forces on a load cell set at three different heights (67, 109, and 152 cm). They were each permitted to experiment with their postures to determine that which they sensed would permit the largest push or pull force, though no direct feedback was given as to their actual performance. Once they achieved what they believed to be their optimal posture, sagittal-plane photographs were taken. The angles of major body joints were then recorded along with the isometric force produced. It is shown that foot placement, handle height, and body postures affect push and pull force capability in a manner that is reasonably logical, using biomechanical concepts. It is proposed that future biomechanical models of push an pull strengths and workplace layouts must be carefully assessed with reference to the postural variations reported.

Comparisons of physiological and perceptual responses in healthy men and women during standardized arm cranking and task-specific pushing–pulling

“…At present, we are not clear if difference in the motion applied during pushing-pulling and arm cranking influenced the physiological differences observed (Table 2). Posture adopted while pushing and pulling with feet stationery is dependent mainly on the vertical height of the handle at the grasp, foot placement at the plane of applied force, and coefficient of friction of the floor/shoe (Martin and Chaffin 1972;Ayoub and McDaniel 1974;Kroemer 1974;Chaffin and Andres 1983;Gagnon et al 1992;James and Cripwell 2005). For maximal isometric effort, Ayoub and McDaniel (1974) recommended an ideal handle placement measured from the floor at 70% of the shoulder height (for pushing) and 40% of the shoulder height (for pulling).…”

“…Greater push-pull forces can be generated when the feet are placed one ahead of the other (Chaffin and Andres 1983). To this effect, the participants were asked to position their feet in a similar fashion during pushingpulling (Fig.…”

“…For static pulling, however, Ayoub and McDaniel (1974) did not report similar duration-related optimum values. One should be cautious, however, in applying the above-mentioned biomechanical factors (Martin and Chaffin 1972;Ayoub and McDaniel 1974;Kroemer 1974;Chaffin and Andres 1983;Gagnon et al 1992;James and Cripwell 2005) that are based on strength (low volume, high intensity) data that reflect primarily of musculoskeletal limitations, and relating them directly to the present investigation of endurancerelated pushing-pulling activity (high volume, low intensity) that essentially influence the cardiovascular system.…”

Dynamic push–pull characteristics at three hand-reach envelopes: Applications for the workplace

“…Dynamic data regarding workplace efforts are lacking, but are vital in order to assure safe and efficient working environments in industrial settings. Isometric pushepull strength profiles in the workspace were reported by a number of investigators (e.g., Chaffin et al, 1983;Davis and Stubbs, 1977;Kroemer and Robinson, 1974;Kumar, 1995b;Tiwari et al, 2010), with comparisons made of positions and reach envelopes between genders. Reach level was found to have a significant effect on women's static pull strength in the seated position Wang, 2004a, 2004b).…”

The evaluation of force exertions and muscle activities when operating a manual guided vehicle

“…The vertical height of the cart handle is an important factor affecting force exertion. Ayoub and McDaniel (1974) and Chaffin et al (1983) stated that the optimal handle height was about 70-80 percent of the shoulder height (91-114 cm) based on the maximum pushing and pulling force. Moreover, Al-Eisawi et al (1999b) reported that the smallest initial pushing force in a horizontal direction is at shoulder height followed by elbow height and knuckle height.…”