The Metabolic Effects of Limb Loaded Wearable Resistance at Varying Loads and Placements While Walking at a Moderate Intensity
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Obesity and cardio metabolic disease have become prevalent in New Zealand. It is clear that New Zealand is now dealing with a public health crisis that has never before been experienced. Diet and exercise habits are key factors that can influence the likelihood of obesity and cardio metabolic disease. Exercise in particular is now more important than ever considering the sedentary nature of the modern way of living. Technology, office work, transportation methods, etc., mean people spend long hours sitting. Researchers have suggested interspersing long periods of sitting with intermittent bouts of physical activity is key. Furthermore, people have a perception that there is a lack of time to set aside for exercise citing many differing life commitments as getting in the way. Thus people who are short on time and often spend long periods each day being sedentary require a novel and effective method of exercising that is easily accessible and able to minimise time cost. Walking is the most common form of exercise in the world and in New Zealand. The 10,000 step rule has been used as a gold standard guideline for daily walking for many years. However, researchers are beginning to show that 10,000 steps may be an unrealistic goal and a guideline that is far too generic, particularly as 10,000 steps takes a long time (~90 mins) and is therefore unappealing to those looking for time-efficient physical activity guidelines. Therefore increasing the metabolic cost of walking may solve the issues outlined above. Walking is an easily accessible form of exercise that can be intermittently dispersed throughout a person’s day and secondly increasing the metabolic cost of walking would decrease the required amount of time set aside for physical activity. Researchers have investigated a variety of ways to increase the metabolic cost of walking such as trunk loading, Nordic walking and limb loading. Trunk loading has been shown to have possible energy-saving effects at low loads and is therefore not ideal. Nordic walking requires poles and training to use the poles effectively, which could be a barrier for participants. However, limb loading has shown promise as it allows for subjects to utilise their normal walking gait while requiring little to no training or experience. Therefore the purpose of this thesis was to examine the metabolic effects of varying peripherally loaded limb conditions using wearable resistance (WR) while walking. Thirteen volunteers from the general population walked at a moderate to vigorous intensity (between 5 km/hr and 6 km/hr) with; no load, leg loading, arm loading and combined arm/leg loading using 2% and 4% of their body mass. The main findings for the 4% loading are reported in this abstract however, significant (p <0.05) but smaller changes were noted for the 2% condition. The main findings were as follows; significant increases in Energy Expenditure (EE) for legs at 4% BM (% Change = 4.9%; ES = 0.22) and combined at 4% BM (% Change = 5.1%; ES 0.24). Similarly there was a significant increase in EE at 4% BM for arms (% Change = 3.1%; ES = 0.17). Position of load did not have a significant effect (p = 0.21) on EE, however the magnitude of loading was found to have a significant effect (p < 0.001) on EE. Significant increases in V̇O2 for legs at 4% BM (% Change = 4.6%; ES = 0.24) and combined at 4% BM (% Change = 5.2%; ES = 0.29). Similarly there was a significant increase in V̇O2 for arms at 4% BM (% Change = 2.9%; ES = 0.19). Position of load did not have a significant effect (p = 0.182) on V̇O2, however the magnitude of loading was found to have a significant effect (p < 0.001) on V̇O2. There were Significant increases in Heart Rate (HR) for legs at 4% BM (% Change = 7.8%%; ES = 0.56) and combined at 4% BM (% Change = 6.6%; ES 0.43). There was a significant increase in HR at 4% BM for arms (% Change = 5.4%; ES = 0.35). Position of load did not have a significant effect (p = 0.069) on HR, however the magnitude of loading was found to have a significant effect (p < 0.001) on HR. Wearable resistance was found to affect the variables of interest; however, it is unlikely the loads and the velocity used would have major effects on the energetic cost of walking (~17 Kcal/h for leg and combined loading conditions at 4% body mass load). However, it should be considered that this additional overload if repeated on many occasions, will have a cumulative effect. Furthermore, because WR provides a mechanical stress overload, it is possible that such loading will strengthen the involved musculature over time.