Objective: This study assessed the effects of acute aerobic exercise and exercise intensity on peripheral blood mononuclear cell (PBMC) expression of energy metabolism-related genes. Hypotheses: It was hypothesized that acute exercise would increase expression of glycolysis-related genes, observable immediately post-exercise (POST), and of mitochondrial respiration-related genes, observable 2h post-exercise (2h POST). It was further hypothesized changes would be greater following heavy- versus moderate-intensity exercise. Methods: Data are from participants in a larger trial (NCT07188389) exhibiting cardiorespiratory fitness (i. e. , VO 2 peak) between the 20th-80th percentile of the sample, that completed acute exercise, and yielded sufficient quality RNA (A260/280 ~= 2, A260/230 ~= 2. 2). The study was approved by the University of Houston Institutional Review Board (ID: STUDY00004272). Acute exercise consisted of two 30-minute cycle ergometer bouts separated by >72 hours: one bout in the moderate- (-10% first ventilatory threshold (VT1) ) and one in the heavy-intensity (+10% VT1) domain. Order of the intensities was randomized, stratified by sex. Blood samples were obtained at rest (PRE), POST, and 2h POST for isolation of PBMCs. PBMC RNA was isolated by TRIzol reagent. Complementary DNA was synthesized from PBMC RNA for analysis of gene expression by RT-PCR. No reverse-transcriptase and no-template controls were run for each sample and target. Expression was quantified relative to PRE and 18s ribosomal RNA using the Pfaffl method. Linear mixed models were used to assess the effects of exercise and exercise intensity on PBMC gene expression. Models were built sequentially to minimize Schwarz’s Bayesian criterion statistic. The alpha-level set to 0. 05. Results: Data of 17 participants were included in analyses (28. 8 +/- 6. 8 years, 24. 3 +/- 4. 2 kg/m², 23. 7 +/- 6. 8 %body fat, 34. 1 +/- 3. 8 ml O 2 /kg/min. ) The exercise bouts were significantly different with regard to VO 2, heart rate, and power (p< 0. 05 for all) and did not exceed the bounds of the prescribed domains; indicating successful implementation of exercise. Sex was considered as a covariate but excluded from final models not improving model fit. A significant time*intensity interaction was observed for hexokinase-2 (HK2) expression such that 2h POST cells showed lower expression versus POST following moderate- but not heavy-intensity (p< 0. 05). Further, 2h POST cells expressed greater HK2 following heavy- versus moderate-intensity (p< 0. 05). No other significant effects of exercise or intensity were observed. However, the main effect of exercise approached significance for lactate dehydrogenase B (LDHb) (p = 0. 051) and carnitine palmitoyl transferase 1a (CPT1a) (p = 0. 070) expression. Summary: Acute aerobic exercise in the moderate- and heavy-intensity domains elicited significant but differing effects on PBMC expression of HK2, and non-significant but consistent effects on expression of LDHb and CPT1a among healthy adults. Conclusion: These data indicate acute aerobic exercise elicits small but detectable changes to PBMC expression of metabolism-related genes, with differential impacts of exercise intensity depending on gene target. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Hodgman et al. (Fri,) studied this question.