Effects Of Prescribed Exercise Training On Lactate Threshold In Cancer Survivors

PURPOSE: Lactate is widely recognized for its role in assessment of fitness, and recent studies have linked lactate to cancer metastasis. Cancer cells adapt their metabolism to promote growth, survival, and proliferation, and a common feature of this altered metabolism is increased glucose uptake and the conversion of glucose to lactate. However, it is unclear whether these adaptations in cancer survivors have an effect on lactate threshold or whether exercise training can increase lactate threshold in this population. Therefore, the purpose of this study was to examine the effects of exercise training on lactate threshold and peak blood lactate during a progressive exercise test in cancer survivors. METHODS: Cancer survivors participated in a 12-week supervised, prescribed exercise program and a progressive treadmill assessment was administered before and after the intervention. During each progressive treadmill exercise assessment, blood lactate was measured using a commercially available lactate analyzer, every two minutes, as well as at termination of the assessment. Lactate data were plotted against metabolic equivalent (MET) and fit with a third order polynomial trendline. Lactate threshold was determined by following the trendline to 1 mmol/L above the initial lactate value and identifying the corresponding equivalent MET value. RESULTS: The variables involved in the study were resting lactate (mmol/L), lactate threshold (METs), and peak lactate (mmol/L). Forty participants met the inclusion criteria. In the experimental group, lactate threshold increased by 0.97 METs after exercise training (Initial: 4.34 ± 1.72 METs; Reassessment: 5.31 ± 2.12 METs; p < 0.01) and peak lactate increased by 1.08 mmol/L (Initial: 5.98 ± 2.22 mmol/L; Reassessment: 7.06 ± 2.76 mmol/L; p < 0.05). No other variables improved significantly in the experimental group or the control group (n = 3). CONCLUSION: To our knowledge, this is the first study to demonstrate that exercise training increases both lactate threshold and peak blood lactate during a progressive exercise bout to volitional fatigue. Even though cancer results in metabolic disruption leading to additional lactate production, these changes do not appear to result in altered blood lactate responses to exercise training or during progressive exercise. NHS Summer CAP Research Grant