def apply_fitness_scaling(
    params: dict,
    *,
    fitness_level: int,
    scaling_config: dict,
    min_reps: int,
    min_reps_strength: int,
    is_strength: bool = False,
) -> dict:
    """Scale workout params based on fitness level."""
    out = dict(params)
    level = fitness_level or 2
    scaling = scaling_config.get(level, scaling_config[2])
    rep_floor = min_reps_strength if is_strength else min_reps

    out['rep_min'] = max(rep_floor, int(out['rep_min'] * scaling['rep_min_mult']))
    out['rep_max'] = max(out['rep_min'], int(out['rep_max'] * scaling['rep_max_mult']))

    rounds_min, rounds_max = out['rounds']
    rounds_min = max(1, rounds_min + scaling['rounds_adj'])
    rounds_max = max(rounds_min, rounds_max + scaling['rounds_adj'])
    out['rounds'] = (rounds_min, rounds_max)

    rest = out.get('rest_between_rounds', 45)
    out['rest_between_rounds'] = max(15, rest + scaling['rest_adj'])

    if level <= 1 and is_strength:
        out['rep_min'] = max(5, out['rep_min'])
        out['rep_max'] = max(out['rep_min'], out['rep_max'])
    return out