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. 2014 Dec 15;592(24):5391-408.
doi: 10.1113/jphysiol.2014.279950. Epub 2014 Nov 10.

Vitamin C and E Supplementation Alters Protein Signalling After a Strength Training Session, but Not Muscle Growth During 10 Weeks of Training

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Vitamin C and E Supplementation Alters Protein Signalling After a Strength Training Session, but Not Muscle Growth During 10 Weeks of Training

G Paulsen et al. J Physiol. .
Free PMC article

Abstract

This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day(-1) and 235 mg day(-1), respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training.

Figures

Figure 1
Figure 1. Timeline for the acute experiment
MVC, maximal voluntary contraction.
Figure 2
Figure 2. Protein immunoblots
Panel of representative protein immunoblots for p38 MAPK (phosphorylated at Thr180/Tyr182 and total), p70S6K (phosphorylated at Thr389 and total), RPS6 (phosphorylated at Ser240/244 and total), eEF-2 (phosphorylated at Thr56 and total) and PRAS40 (phosphorylated at Thr246 and total). All these samples were run in duplicates. 4EBP1 (phosphorylated at Thr37/46 and total), ERK1/2 (phosphorylated at Thr202/Tyr204 and total) and AMPKα (phosphorylated at Thr172 and total) were run in singles with GAPDH as loading control. All samples from each participant were always quantified in the same blot.
Figure 3
Figure 3. Changes in 1 repetition maximum (1RM) in the upper body (biceps curl and triceps press) and lower body (knee-extensions and knee-flexion) exercises after 10 weeks of strength training
Boxplots show maximum–minimum values, 25–75th percentiles, and medians.•, outliers (Tukey's rule); *within-group changes. The P value for a between-group comparison is given in the figure (statistical tendency). C + E vit, vitamin C and E group.
Figure 4
Figure 4. Changes in maximal isometric contraction force
Upper panel: changes in maximal voluntary contraction force (MVC) during isometric conditions (90 deg in the knee-joint) after vs. before 10 weeks of strength training. Lower panel: changes in specific strength (MVC force divided by quadriceps cross-sectional area) after vs. before 10 weeks of strength training. Boxplots show maximum–minimum values, 25–75th percentiles, and medians. •, outliers (Tukey's rule); *within-group changes. The P value for a between-group comparison (statistical tendency) is given in the figure. C + E vit, vitamin C and E group.
Figure 5
Figure 5. Changes in muscle cross-sectional area and appendicular lean mass
Upper and middle panels: changes in cross-sectional area (CSA) of upper arm (m. brachialis, m. biceps brachii, m. triceps brachii) and thigh (m. quadriceps and hamstring muscles) after vs. before 10 weeks of strength training. Lower panel: appendicular muscle mass (arms and legs) after vs. before 10 weeks of strength training. Boxplots show maximum–minimum values, 25–75th percentiles, and medians. •, outliers (Tukey's rule); *within-group changes. C + E vit, vitamin C and E group.
Figure 6
Figure 6. Changes in maximal voluntary contraction (MVC) during isometric conditions (90 deg in the knee-joint) after a single session of strength training
Values are means and standard deviations. *Within-group changes compared to before (pre) exercise. C + E vit, vitamin C and E group.
Figure 7
Figure 7. Muscle protein fractional synthetic rate and changes in total protein ubiquitination
Muscle protein fractional synthetic rate (FSR) 80–30 min before (pre) and 100–150 min after (post) a single session of strength training (upper panel). Changes in total ubiquitination 100 and 150 min after a single session of strength training, compared to before (pre 1) exercise levels (lower panel). Pre 1, biopsy obtained 80 min before exercise. Pre 2, biopsy obtained 30 min before exercise. Boxplots show maximum–minimum values, 25–75th percentiles, and medians. *Within-group changes. C + E vit, vitamin C and E group.
Figure 8
Figure 8. Changes in the phosphorylation status of p38 MAPK upper and lower bands, and ERK1/2 100 and 150 min after a single session of strength training, compared to before (pre 1) exercise levels
Pre 1, biopsy obtained 80 min before exercise. Pre 2, biopsy obtained 30 min before exercise. •, outliers (Tukey's rule); #difference between groups; *within-group changes from pre 1. C + E vit, vitamin C and E group.
Figure 9
Figure 9. Changes in the phosphorylation status of AMPKα, PRAS40, 4EBP1, p70S6K, RPS6 and eEF-2 100 and 150 min after a single session of strength training, compared to before (pre 1) exercise levels
Pre 1, biopsy obtained 80 min before exercise. Pre 2, biopsy obtained 30 min before exercise. Boxplots show maximum–minimum values, 25–75th percentiles, and medians. •, outliers (Tukey's rule); #difference between groups; *within-group changes from pre 1. C + E vit, vitamin C and E group.

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