Monitoring Blood Biomarkers and Training Load Throughout a Collegiate Soccer Season

• Published in: Journal of strength and conditioning research 2019-11, Vol.33 (11), p.3065-3077
• Main Authors: Huggins, Robert A, Fortunati, Andrea R, Curtis, Ryan M, Looney, David P, West, Chris A, Lee, Elaine C, Fragala, Maren S, Hall, Matthew L, Casa, Douglas J
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adolescent; Alanine; Alanine transaminase; Alanine Transaminase - blood; Albumin; Aspartate aminotransferase; Aspartate Aminotransferases - blood; Athletic Performance - physiology; Biomarkers; Biomarkers - blood; Body fat; Body mass; Calcium; Cholesterol; College sports; Cortisol; Exercise Test; Fatty acids; Fatty Acids - blood; Fitness; Globulins; Hematocrit; High density lipoprotein; Humans; Hydrocortisone - blood; Inflammation; Iron; Lipoproteins - blood; Low density lipoprotein; Male; Minerals - blood; Physical Conditioning, Human - physiology; Physical Exertion - physiology; Physical Fitness - physiology; Physical training; Selenium; Serum Albumin - metabolism; Serum Globulins - metabolism; Soccer; Soccer - physiology; Sports training; Testosterone; Testosterone - blood; Universities; Vitamin D; Vitamin E; Vitamins - blood; Young Adult
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0000000000002622

ABSTRACTHuggins, RA, Fortunati, AR, Curtis, RM, Looney, DP, West, CA, Lee, EC, Fragala, MS, Hall, ML, and Casa, DJ. Monitoring blood biomarkers and training load throughout a collegiate soccer season. J Strength Cond Res 33(11)3065–3077, 2019—This observational study aimed to characterize the responses of a comprehensive panel of biomarkers, observed ranges, training load (TL) metrics, and performance throughout the collegiate soccer season (August–November). Biomarkers (n = 92) were collected before the start of pre-season (PS), in-season weeks (W)1, W4, W8, and W12 in NCAA Division I male soccer players (n = 20, mean ± SD; age = 21 ± 1 years, height = 180 ± 6 cm, body mass = 78.19 ± 6.3 kg, body fat = 12.0 ± 2.6%, VO2max 51.5 ± 5.1 ml·kg·min). Fitness tests were measured at PS, and W12 and TL was monitored daily. Changes in biomarkers and performance were calculated via separate repeated-measures analysis of variance. Despite similar fitness (p > 0.05), endocrine, muscle, inflammatory, and immune markers changed over time (p < 0.05). Total and free testosterone was lower in W1 vs. PS, whereas free cortisol remained unchanged at PS, W1, and W4 (>0.94 mg·dL). Oxygen transport and iron metabolism markers remained unchanged except for HCT (W1 vs. PS) and total iron binding capacity (W8–W12 vs. W1). Hepatic markers albumin, globulin, albumin:globulin, and total protein levels were elevated (p < 0.05) at W12 vs. W1, whereas aspartate aminotransferase and alanine aminotransferase levels were elevated at W1–W12 and W8–W12 vs. PS, respectively. Vitamin E, zinc, selenium, and calcium levels were elevated (p < 0.05) at W12 vs. W1, whereas Vitamin D was decreased (p < 0.05). Fatty acids and cardiovascular markers (omega-3 index, cholesterol:high-density lipoprotein [HDL], docosahexenoic acid, low-density lipoprotein [LDL], direct LDL, non-HDL, ApoB) were reduced at W1 vs. PS (p ≤ 0.05). Immune, lipid, and muscle damage biomarkers were frequently outside clinical reference ranges. Routine biomarker monitoring revealed subclinical and clinical changes, suggesting soccer-specific reference ranges. Biomarker monitoring may augment positive adaptation and reduce injuries from stressors incurred during soccer.