Gjovaag Terje, Mirtaheri Peyman, Starholm Inger Marie
1 Oslo and Akershus University College, Oslo, Norway.
2 Faculty of Technology, Art and Design, Oslo and Akershus University College, Oslo, Norway.
Prosthet Orthot Int. 2018 Jun;42(3):304-310. doi: 10.1177/0309364617740237. Epub 2017 Nov 9.
Studies suggest that the energy expenditure of healthy persons (control) during walking with the preferred walking speed in steady-state conditions is dominated by fat oxidation. Conversely, carbohydrate and fat oxidation during walking is little investigated in transfemoral amputees.
To investigate carbohydrate and fat oxidation, energy cost of walking, and percent utilization of maximal aerobic capacity [Formula: see text]during walking.
Eight transfemoral amputees and controls walked with their preferred walking speed and speeds 12.5% and 25% slower and faster than their preferred walking speed.
Energy expenditure and fuel utilization were measured using a portable metabolic analyzer. Metabolic values are means ± standard deviation.
For transfemoral amputees (37.0 ± 10.9 years) and controls (39.0 ± 12.3 years), fat utilization at the preferred walking speed was 44.8% ± 7.2% and 45.0% ± 7.2% of the total energy expenditure, respectively. The preferred walking speed of the transfemoral amputees and controls was close to a metabolic cross-over speed, which is the speed where carbohydrate utilization increases steeply and fat utilization decreases. When walking fast, at 90 m min (preferred walking speed plus 25%), transfemoral amputees utilized 70.7% ± 5.6% of their [Formula: see text], while the controls utilized 30.9% ± 4.5% ( p < 0.001) at the matching speed (control preferred walking speed). At 90 m min, carbohydrate utilization was 78% ± 4.7% and 55.2% ± 7.2% of the total energy expenditure for the transfemoral amputees and controls, respectively ( p < 0.01). Compared to the control, energy cost of walking was higher for the transfemoral amputees at all speeds (all comparisons; p < 0.001).
At the preferred walking speed, carbohydrate, not fat, dominates energy expenditure of both transfemoral amputees and controls. For the transfemoral amputees, consequences of fast walking are very high [Formula: see text] utilization and rate of carbohydrate oxidation. Clinical relevance Research on the relationships between physical effort and fuel partitioning during ambulation could provide important insights for exercise-rehabilitation programs for lower limb amputees (LLA). Regular endurance exercise will improve maximal aerobic capacity and enable LLA to walk faster and at the same time expend less energy and improve fat utilization.
研究表明，健康人（对照组）在稳态条件下以首选步行速度行走时，能量消耗主要由脂肪氧化主导。相反，经股截肢者行走过程中的碳水化合物和脂肪氧化情况鲜有研究。
研究行走过程中的碳水化合物和脂肪氧化、行走的能量消耗以及最大有氧能力[公式：见原文]的利用率百分比。
8名经股截肢者和对照组人员分别以各自的首选步行速度以及比首选速度慢12.5%和快25%的速度行走。
使用便携式代谢分析仪测量能量消耗和燃料利用率。代谢值为平均值±标准差。
对于经股截肢者（37.0±10.9岁）和对照组（39.0±12.3岁），在首选步行速度下，脂肪利用率分别占总能量消耗的44.8%±7.2%和45.0%±7.2%。经股截肢者和对照组的首选步行速度接近代谢交叉速度，即碳水化合物利用率急剧增加而脂肪利用率下降的速度。当快速行走时，即速度为90米/分钟（首选步行速度加25%）时，经股截肢者在匹配速度（对照组首选步行速度）下的最大有氧能力[公式：见原文]利用率为70.7%±5.6%，而对照组为30.9%±4.5%（p<0.001）。在90米/分钟时，经股截肢者和对照组的碳水化合物利用率分别占总能量消耗的78%±4.7%和55.2%±7.2%（p<0.01）。与对照组相比，经股截肢者在所有速度下的行走能量消耗均更高（所有比较；p<0.001）。
在首选步行速度下，经股截肢者和对照组的能量消耗均以碳水化合物而非脂肪为主。对于经股截肢者而言，快速行走的后果是最大有氧能力[公式：见原文]利用率和碳水化合物氧化率非常高。临床相关性 关于行走过程中体力消耗与燃料分配之间关系的研究，可为下肢截肢者（LLA）的运动康复计划提供重要见解。定期进行耐力运动将提高最大有氧能力，并使LLA能够走得更快，同时消耗更少的能量并提高脂肪利用率。
