Application of FT-IR Spectrometry to Determine the Global Metabolic Adaptations to Physical Conditioning in Sportsmen

Abstract

Global metabolic adaptations to physical conditioning were described in 15 subjects by FT-IR spectrometry as the method allowed determination of glucose (Glc), lactate (La), glycerol, triglycerides (TG), fatty acyl moieties (FAM), and total amino acids plasma concentrations. Subtraction of plasma FT-IR spectra obtained at resting state from the exercise spectra also allowed determination of the biomolecular response to exercise. On week 1, exercise induced a transient hypoglycemia, a lactatemia increase of 153%, a FAM depletion of 27%, and a TG concentration decrease of 28%. Protein contents increased by 2%, but these were partly catabolized for amino acid supply (+27%), suggesting an important metabolic stress during exercise. On week 3, exercise hypoglycemia had disappeared, lactate increase was diminished by 91%, TG contents were decreased by 14%, and proteins and amino acids exhibited higher absorption increases. On week 5, TG and FAM concentrations were markedly increased during exercise, protein absorption was still increased (+9%), but amino acid blood release was diminished by 81%. These results described positive adaptations to training. Furthermore, FAM concentration could be determined from plasma FT-IR spectra by using the 2996–2819 cm⁻¹ spectral area [ν_as(CH₃), ν_as(CH₂), ν_s(CH₃), and ν_s(CH₂) absorbance; 0.82 mMol·L⁻¹, a.u. cm⁻¹], as well as for amino acid concentration by using the ν(COO⁻) spectral area (1430–1360 cm⁻¹; 0.062 g·L⁻¹, a.u. × cm⁻¹). FT-IR spectrometry was useful to determine simultaneously various plasma concentrations and most of the biomolecular changes through successive samples.