Why is it that some people slog away at the gym for years without any visible big differences in their physique while others seem to put on the trainers and achieve toned and taut abs almost overnight?
New research would appear to back up the theory that while some people put in a lot of time with apparently little to show for it, others achieve big results with seemingly little effort. Could it be that some people respond better to exercise than others? Could your lack of a six-pack be down to the fact that you are, in fact, a 'non-responder'?
Researchers from Queen's University in Canada have found that we are each programmed to respond to different types of exercises. Lead author of the study Jacob Bonafiglia says that by following gym trends or even entering a marathon or triathlon, we may unwittingly be setting ourselves up for failure.
"What we've discovered is that individuals may be more sensitive to certain exercise training protocols than others. What works for one person doesn't necessarily work for the next," says Bonafiglia.
Earlier this month Roz Purcell (26) revealed that she works out 10-11 times a week to stay at her peak, both mentally and physically. "I'm always training. For me, it's what I enjoy doing. I don't want to sound excessive but I would train 10 to 11 times a week - a mixture of boxing, yoga, legs, arms and different classes. I'd take a rest day once a fortnight but if I wake up sore, I'll take another one," she said.
For most people making a workout fit into your schedule a couple of times a week is just about manageable. So how do we ensure we are doing enough and make sure we are doing the right kinds of exercises that suit us best so we can see results? Professor Niall Moyna from the Department of Health and Human Performance at Dublin City University says the non-responders theory has been around for a long time, and that we have known for many years through various studies about people who respond better to exercise than others.
However, Prof Moyna says the fact is everyone responds and those who are not seeing any changes are simply not getting a severe enough stimulus. Just because you can't see big changes, he says, doesn't mean that phenomenal and far more important changes aren't happening underneath the surface.
"Their metabolic health could be changing, their heart is remodelling. Changes don't always manifest themselves in performance. Any form of exercise is extremely beneficial," he says.
Fitness expert Damien Maher, who runs Be Fit for Life gym in Dublin's Sandyford, says people change their shape by changing their behaviour outside the gym. And he says people can set themselves up for failure by comparing themselves to others who they perceive to have the perfect body. "You immediately feel inadequate. When you're comparing yourself to someone else, you're minimising yourself," he says.
Damien also says people embark on a training programme and say they are going to work out six or seven times a week; when they can't achieve this they feel disillusioned. "People want to go from zero to hero in record time," he says.
However, Damien says he doesn't buy into the non-responders theory.
"It's basically saying 'it doesn't work for me - I tried it before'. It's just another excuse. For some people the changes are happening under the surface and it's like the volcano, you don't see it till it explodes. If you look at the most successful people, they are on the verge of quitting and then they succeed," says Damien.
"Many people go to a gym and wonder why nothing is happening. They think by joining and paying the money that the job is done. The hard part is changing your lifestyle outside the gym and doing the work. If you want to change, you have to commit. Most people don't commit," he says.
Donegal mum of four Mary T McConnellogue (43) says she had been getting nowhere fast on a treadmill at home. While she'd always been a size 10, Mary T says she gradually noticed the weight go on after the birth of her fourth child eight years ago and when she looked at photos from a family holiday last summer, she felt she had to get in shape again.
"I started walking and for the first month I was getting out every other day. Some days I did 5k, others 10k. Because my body wasn't used to the exercise, the weight came off quite quickly. I also cut down on things like chocolate and crisps but I didn't want to diet. I had the attitude of food is my friend, it's not doing me any harm," she says.
Mary T says she never plans how she's going to exercise in a day or has a specific training schedule; she simply builds it into her day and works around the kids and college, where she is studying accountancy.
"I'd still walk if I can get out. If I can't get out because the kids are home, I'll just walk around the garden. If they're outside playing basketball, I'll join in and I'm spending time with them as well as exercising. If we go to the beach, we'll play tennis. I have a skipping rope so if I'm outside doing a few jobs, I might skip for 10 minutes. I incorporate it all into my routine. I'm really enjoying it and it's increased my confidence," she says.
"Before I started all this I thought what's the point? I thought I'll never get my youthful shape back. I thought maybe this is just the forties spread.
"I had a treadmill at home but I didn't enjoy it and it never shifted the weight. Even though I was running and running, I still stayed the same size. It didn't work for me the way getting out in the fresh air did," says Mary T.
"Now I go out walking and I have my playlist of happy music - a bit of Bruce Springsteen and Justin Timberlake, anything upbeat, and I walk. It boosts your whole system...I still have my meringues with cream if I want them. I say this isn't calorific - it's vitalific," she says.
Paul Byrne who runs BodyByrne Fitness in Dublin City adds that the key to achieving results when you're working out is finding something you enjoy and mixing it up regularly. He says if people find what they're doing isn't having any effect, they need to look at what they're doing outside the gym.
"I hear people say they are burning hundreds of calories at the gym but they're taking in more than they're burning when they go for a cappuccino and sweet snack afterwards," he says.
He also says it's important to change to see results.
"If you are doing the same thing, week in week out, you won't see any improvement. You will get disheartened. Mix it up every four weeks and find something you enjoy."
Personal trainer and pilates teacher Áine Crossan believes people need to mix up their exercise routines every few months to avoid getting stuck in a rut.
Based in Letterkenny, Co Donegal, Áine says people should look outside the box when it comes to their routine and instead of spending hours on a treadmill, jump on a trampoline.
Mum to Molly (8), Áine says parents can use their children's activities to jump start their own instead of sitting around; do a class with them or join them in their games.
"Try and incorporate your activities with kids; trampolining, bowling, cycling, walking, bodyboarding, or hill-walking for example. I have tried many new things outside my comfort zone through my child and I love them," she says.
"Switch it up. Change something about your workout every six weeks. If you're walking, take a route you have never taken before. If you are cycling, do sprints with the lowest gear and fastest speed or do high gears or hill climbs. You can do the same exercise, but change it around," says Áine.
"Be realistic. If you are exhausted you may be adrenaline and cortisol fatigued. Better to go on a cleansing diet and recover from burn out than do high adrenaline sport. You can't out-train a bad diet."
She adds: "Get a personal trainer if you are really not motivated. Make sure to keep things low impact and low weight. Be clear with your trainer. Their aim is to get you the best results but if the workout is too difficult or you are too tired, communicate that. Communication, whether in a class or with a trainer, is key. If they don't know they can't help."
Áine also advises checking out your local resource, community and family centres for classes and walking groups.