Striker Mike Phenix says AFC Telford United are finding it hard to bridge the fitness gap on full-time clubs in the Conference Premier.
Telford have remained a part-time outfit since being promoted back to the top flight of English non-league football in April, in contrast to the majority of Conference Premier clubs.
"We're only training twice a week," Phenix told BBC Radio Shropshire.
"But we're up against teams who train three or four times a week."
He added: "They're doing probably double the fitness work we do, perhaps more.
"For us, it's just about using the time wisely and getting in your fitness when you can."
Phenix hit eight goals from midfield last season despite having to cope with the effects of colitis, the same bowel condition which forced Manchester United midfielder Darren Fletcher to miss nearly 12 months of football.
The 25-year-old said regular medication has helped him, although he has also had to contend with some unwelcome side effects.
|AFC Telford United's summer signings|
|Goalkeeper: Jonathan Hedge (Grimsby Town)|
|Defenders: Steve Akrigg (Southport), Rod McDonald (Hereford United), Kristian Platt (Stalybridge Celtic)|
|Midfielders: Jordan Deacey (Bradford Park Avenue), Josh Hancock (Witton Albion), Godfrey Poku (Mansfield Town)|
|Striker: Sam Smith (Hereford United)|
"The medication makes me tired," he said.
"But I feel like I now have it under control and don't have the same flare-ups."
Phenix, who joined Telford from Skelmersdale United in the summer of 2013, has switched to a more forward role this season and scored two goals in Monday's 3-3 draw against Southport.
"I've found it hard stepping up a level to the Conference and coming up against big centre-halves," he said.
"I had a word with the manager and he says playing up there is about working hard, being alive in the box and hoping that things fall your way. And it's great to have opened my account for the season."
Telford are still waiting for their first win of the season after five games and face fellow early-season strugglers Dartford on Saturday.
"We know where we're going wrong," added Phenix.
"It's up to us to change it."