The degree of weightlessness of apparently healthy adults in four standing postures during immersion in water to anterior superior iliac spine level was investigated in this study. The mean percentage weight bearing (52.3 ± 5.8) obtained in the erect standing (ES) posture for this study falls within the range reported by the previous authors [8, 9]. The similarity in the selection of the participants coupled with the conformity to the protocol in all the studies might have accounted for the consistent finding.
However, the results of this study did not agree with our hypothesis that variations in standing posture would not significantly influence the PWB. The assumption of four different standing postures indeed significantly affected the participants’ PWB while immersed to the anterior superior iliac spine level. Participants had significantly lower PWB in GIPS and ISHS postures than in ES and HGITSS standing postures, and significantly lower PWB in HGITSS than in ES postures. It thus implies that axial loading of weight bearing joints varies with different postures assumed in static standing with more weight being borne in erect standing than in the three derived standing postures. Conversely, PWB of the participants in GIPS and ISHS postures were not significantly different. The utilization of the outcomes of this result will be aptly informed by the goals of hydro pool exercises. Whilst GIPS and ISHS postures will be ideal for athletes who are recovering from bouts of sports participation or for relaxation, erect standing and half grasp inclined standing could be utilized during controlled weight bearing exercises in clinical practice.
Clinically, physiotherapists and sports medicine professionals find hydro pool useful as a package of therapeutic techniques either for rehabilitation or for general health promotion. Studies have established the potency of erect standing posture during immersion in enhancing recovery from bouts of strenuous exercises , enhancing fetal descent in pregnant women during labour process , allowing weight bearing moderation on the acute rheumatic or arthritic joints [4, 6, 7] and in patients recuperating from knee or hip arthroplasty . The outcomes of this study could therefore provide wider options in the use of postures during hydro pool application.
Although, no literature is available with which to compare the results in the derived standing postures employed in the present study, the findings could be conceptually hinged on the effects of the alteration of body segments, causing non-alignment of the upward bouyant force with the downward gravitational force on the immersed individual [11–13]. The resultant turning effect (moment of buoyancy) from this disproportionate forces could cause displacement of line of forces beyond the center of bouyancy as well as the base of support of an individual thus influencing the amount of weight that would be transfered to the lower limbs . This implies that, any movement or alteration of the limbs, trunk and head which alters the body’s shape whether above or below the surface of water will produce rotational effects, the amount of which depends on the degree of displacement, as will occur in any alteration in shape due to disability. Although, this submission is analogous to partial weight bearing during aided ambulation on land, the biophysical properties of water will expectedly enhance the biomechanics in the weight bearing joints.
Findings from this study indicate that the participants’ height and body mass index were significant predictors of percentage weight bearing (PWB). However, age was not a significant determinant of PWB in all standing postures when submerged to anterior superior iliac spine. It thus implies that age may not be important in determining PWB of the participants in all standing postures at this level of immersion. A similar study , however reported strong predictability of PWB in ES posture at ASIS by age, body weight on land and percent body fat. Although, the present study adopted different predicting variables from the previous study, age which is a common variable in both studies was not statitistcally significant in predicting PWB in the present study. Further discussion of findings on PWB in this study is hampered by the scarcity of literature on derived standing postures in research. From anectodal observation and search of literature, none of the inclined standing postures has been investigated for PWB apart from erect standing posture. Generally, there is an apparent dearth of research and policy on PWB for hydrotherapy uses in Sub-Saharan Africa. This situation thus calls for future efforts on this topic by sampling individuals with wide age gap.
The present study was limited by the high sensitivity of the adapted weight measuring scale used in this study. The water turbulence constantly caused transient fluctuation by a fraction of gram as read on the digital monitor placed by the pool side. As a result, the stable scores could only be read transiently within 2–5 seconds. The use of the specially devised force platform for measuring body weight under water could have been more appropriate.