Seasonal Variation of Red Blood Cell Variables in Physically Inactive Men: Effects of Strength Training

Abstract

The purpose of this study was to investigate if strength training affects red blood cell variables in physically inactive men when taking into account seasonal variations. Seventy-four men aged 20 - 45 were randomly assigned to training (n = 52) and control (n = 22) groups. Training group underwent 20-week progressive strength training. Body composition and maximal voluntary contraction (MVC) during knee extension were measured before and after intervention. Fasting blood samples were analysed for haematocrit (Hct), count of red blood cells (RBC), haemoglobin (Hb), mean cell haemoglobin concentration (MCHC), and mean cell volume (MCV) at baseline, 10-week and 20-week follow-up. MVC and lean body mass increased in the training group. Hct, Hb and MCHC showed seasonal variation in the control group. The training group increased their Hct from 44.7 ± 2.6 % to 45.4 ± 2.5 % (p = 0.026) while the control group decreased their Hct from 44.3 ± 2.2 % to 43.1 ± 2.6 % (p = 0.037) after 20-week intervention. By contrast to the control group, the training group increased their Hct (p = 0.001), RBC (p = 0.005) and decreased their MCHC (p < 0.001) from 10-week to 20-week follow-up. We concluded that strength training could affect seasonal variation patterns of red cell variables. Unlike “sport anaemia” induced by endurance training, 20-week strength training elevated Hct.

Key words

resistance training - haematocrit - biological rhythm

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