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SHORT-TERM LOW-CARBOHYDRATE DIET DISSOCIATES LACTATE AND AMMONIA THRESHOLDS IN MEN
- Source :
- Journal of Strength and Conditioning Research. 18:260-265
- Publication Year :
- 2004
- Publisher :
- Ovid Technologies (Wolters Kluwer Health), 2004.
-
Abstract
- A low-carbohydrate (L-CHO) diet has been shown to shift the lactate threshold toward higher workloads. The aim of the present study was to examine the effect of an L-CHO diet on the ammonia threshold and to compare it with the lactate threshold in men. The plasma catecholamine threshold was also measured. Eight young, untrained men participated in the study. Two exercise tests with graded workload were performed. The workload was increased every 3 minutes by 40 W until volitional exhaustion. The first test was performed after 3 days of a controlled mixed diet. After the first test, the mixed diet was switched to a L-CHO diet. Three days later the same test was repeated. The blood concentration of lactate, ammonia, noradrenaline, and adrenaline was measured before and after each workload in both groups. It was found that the concentration of the examined compounds in the blood increases exponentially with graded workload after each kind of diet. This led us to calculate the blood ammonia, lactate, epinephrine, and norepinephrine thresholds. The thresholds were defined as points at which the concentration of a given compound starts to increase in a nonlinear fashion, which is calculated using 2 segmental linear regressions. After the mixed diet, the threshold for each compound occurs at the same workload. The L-CHO diet resulted in dissociation of the lactate threshold from the ammonia threshold: the lactate threshold was shifted toward a higher workload, whereas the ammonia threshold was shifted toward a lower workload. The norepinephrine threshold was also shifted toward a lower workload, and the epinephrine threshold remained unchanged. The results obtained indicate that an L-CHO diet accelerates production of ammonia and delays production of lactate during graded exercise, as well as that diet must be strictly controlled when ammonia and lactate thresholds are measured.
- Subjects :
- Adult
Male
medicine.medical_specialty
Anaerobic Threshold
Epinephrine
Carbohydrates
Physical Therapy, Sports Therapy and Rehabilitation
Workload
Norepinephrine (medication)
Ammonia
chemistry.chemical_compound
Norepinephrine
Animal science
medicine
Humans
Orthopedics and Sports Medicine
Lactic Acid
Low carbohydrate
Exercise
Mixed diet
Analysis of Variance
business.industry
Lactate threshold
General Medicine
Surgery
Diet
chemistry
Catecholamine
business
medicine.drug
Subjects
Details
- ISSN :
- 10648011
- Volume :
- 18
- Database :
- OpenAIRE
- Journal :
- Journal of Strength and Conditioning Research
- Accession number :
- edsair.doi.dedup.....f787926ce3960e96f5cbbf252b0783cd