# The effect of nimesulide on skeletal muscle hypertrophy and load progression after 8 weeks of resistance training in wistar rats

## TL;DR

This study found that nimesulide use during resistance training in rats led to greater muscle growth compared to training alone.

## Contribution

The novel finding is that nimesulide enhances muscle hypertrophy in rats during resistance training without affecting training load.

## Key findings

- Nimesulide-treated rats showed greater hypertrophy in the FHL muscle when normalized to body mass.
- Muscle strength increased in both trained groups compared to controls.
- Nimesulide did not alter training load progression between groups.

## Abstract

Resistance training is currently a widely targeted practice due to its ability to induce vital adaptations resulting from increased muscle strength (MS) and hypertrophy. There are reports of the concomitant use of nonsteroidal anti-inflammatory drugs with this practice for pain relief, which arises from the adaptive signaling of training. Based on this, the present study aimed to investigate whether the use of nimesulide concomitant with training could interfere with MS and hypertrophy. The sample consisted of 18 male Wistar rats, aged 91 days, with a body mass of 331 ± 20 g, divided into three groups: Control (CTRL, n = 4); Trained (TR, n = 7); and Trained and Treated with nimesulide (COMB, n = 7). The training protocol followed the ladder-climbing model. Nimesulide was administered orally at a dose of 2.5 mg/kg every day after training. Tissue collection of the Flexor Hallucis Longus (FHL) muscle was performed two days after the last training session. After eight weeks of the training protocol, a significant increase in MS was observed in TR and COMB compared to CTRL (p < 0.05). A significant increase in FHL muscle volume was observed in COMB compared to CTRL and TR only when muscle mass was normalized to body mass (p < 0.05), whereas no significant differences were detected among groups for absolute FHL mass. Additionally, there were no differences in training load or volume between COMB and TR (p ≥ 0.05). Therefore, based on the results, it is concluded that the administration of nimesulide during eight weeks of training promoted a greater hypertrophic response of the FHL muscle in rats.

The online version contains supplementary material available at 10.1007/s10974-026-09724-3.