# Muscle metabolic responses to a 5v5 football game in trained female football players

## TL;DR

This study looked at how muscle metabolism changes during a 5v5 football game in trained women, finding significant metabolic stress despite low physical load.

## Contribution

The novel contribution is quantifying muscle metabolic responses to 5v5 SSG in trained female football players.

## Key findings

- Muscle lactate nearly doubled post-game, indicating significant anaerobic activity.
- Muscle glycogen and creatine phosphate levels decreased significantly during the game.
- Heart rate and distance covered were high, but decreased in later game periods.

## Abstract

The study examined the acute muscle and systemic physiological responses to a 5v5 small-sided game (SSG) of football in trained female players.

Ten trained female football players (age: 24.5 ± 1.9 years, height: 169 ± 5 cm, weight: 67.0 ± 8.0 kg, fat%: 24.8 ± 7.6%) completed four 12-min periods of play (P1-P4) with 4-min passive recovery. Muscle biopsies were obtained from m. vastus lateralis pre- and post-game, and analyzed for glycogen, creatine phosphate (CP), ATP, and lactate. Blood lactate was measured pre-, mid-, and post-game. Heart rate and movement patterns were recorded continuously using chest-worn sensors.

Muscle lactate nearly doubled (mean [95CI], 4.8 [2.5, 7.1] to 8.8 [6.5, 11.0] mmol/kg dw; P < 0.01), while blood lactate rose 57% mid-game and 80% post-game (P < 0.01). Muscle CP declined 22% (P < 0.01), muscle ATP remained unchanged, and muscle glycogen declined (P < 0.01) from 349 [299, 399] at baseline to 275 [225, 325] mmol/kg dw post-game. Average and peak heart rates reached 82 [78, 86] % and 93 [89, 97] %HRmax, respectively, while players covered 3805 [3308, 4303] m in total, with greater distance in the first period compared to later periods (P2–P4, P < 0.05).

These findings indicate that 5v5 SSG impose a notable muscle metabolic load in trained female players, taxing both aerobic and anaerobic energy systems despite a relatively low external load. SSG may be a training modality for improving sport-specific fitness in trained young female players, but intervention studies are required to confirm adaptations. Inference is limited by the small sample and absence of control for menstrual phase and pre-exercise nutrition.