Dr Catherine Norton, University of Limerick. Image: Dr Catherine Norton
Dr Catherine Norton at UL is examining how the timing of nutrition affects performance and muscle health in athletes and older people. She spoke to Dr Claire O’Connell.
For athletes, whether they are looking to cross the line with a new world record or pace themselves through a gruelling match, timing is everything. Could getting the timing right with their diet also help them gain peak performance?
Sport and exercise nutritionist and registered dietician Dr Catherine Norton at the University of Limerick (UL) is figuring out how to fine-tune the protein intake of athletes to improve recovery from training, as well as facilitating muscle growth.
But it’s not only the elite sportspeople who are benefiting from the science – her work is also providing insights into how the rest of us can get more out of our activities, and protect our muscles as we age.
Age and muscle loss
Norton started her research in the area at UL’s Department of Physical Education and Sport Sciences. As part of the Food for Health Ireland consortium, her PhD looked at whether bioactive proteins isolated from milk could help to reduce muscle loss as we age.
“A lot of people are familiar with the fact that we lose bone density as we get older but, from the fourth decade on, there is a measurable loss of muscle mass on an annual basis,” she explained.
Exercise – and particularly resistance exercise – is a great way to protect against muscle loss, but Norton wanted to see if optimising dietary protein could offer protection, too.
‘Exercise is still the most potent stimulator for building muscle, but we have shown that redistributing daily protein intake and optimising the quality of that protein can also have benefits’
– DR CATHERINE NORTON
Protein around the clock
The study recruited 148 healthy older adults aged between 50 and 70, and step one was to find out more about the protein currently in their diets. When Norton analysed the results, a strong pattern jumped out.
“Even though everyone was taking in the recommended amount of protein on a daily basis, the nuances of the total intake were not attended to. Many participants were taking the bulk of their total daily protein intake in their main evening meal rather than spreading the protein out across a few meals during the day,” she said.
“That frequency pattern, where you might get all your protein from the salmon or chicken or beef in the evening, might mean you are not getting the benefits of protein for protecting muscles at other times of the day, too.”
If you consume three main meals each day, there are around 1,095 opportunities each year to switch on the cellular mechanism to build muscle, but the research showed that the participants only activated this mechanism once daily. “Those sub-optimal meals with less protein represent lots of missed opportunity to prevent muscle mass loss with ageing,” said Norton.
Next, 60 participants took part in a six-month study to see whether taking a dairy protein supplement at breakfast and lunch had an effect on their muscle mass. The results? Those who took no protein supplement lost muscle mass, as people their age typically would, but the people who took the milk-derived protein at breakfast and lunch saw an increase in muscle mass, even with no extra physical activity.
A patent is now pending on the protein supplement, and Norton believes it could help people to age more healthily. “Exercise is still the most potent stimulator for building muscle, but we have shown that redistributing daily protein intake and optimising the quality of that protein can also have benefits,” she said.
Converting nutrition to performance
Following her successful PhD, Norton went to work with Munster Rugby for three seasons where, as head of performance nutrition, she was in charge of telling giants of Irish rugby what to eat. “It all depends on how you present the message,” said Norton, whose father played rugby for Munster and Ireland, and who has had a lifelong interest in the sport.
“As with everyone, you have to appeal to their needs. There is little point in telling them that changing eating habits now will reduce the risk of osteoporosis in your 70s. They are focused on performing well in the 80 minutes of a match. So, you tell them that this dietary change will help them to run faster, get stronger and recover better, and that gets everyone onside.”
Around a year ago, Norton returned to UL as a co-principal investigator with Food for Health Ireland, where she is working with high-performance athletes to personalise their nutrition for performance. “We are looking at how the timing of protein intake helps trained athletes with muscle building and recovery from resistance and endurance training,” she explained.
Just as with the healthy older adults in her previous work, a key aspect to the research is figuring out the usual patterns of protein intake for individual athletes. “We ask them to keep seven-day food, fluid and activity diaries; the athletes wear on-body technology that monitors activity patterns; we analyse body mass and composition; and, most importantly, we determine the specific needs of the individual. Then we prescribe bespoke nutrition for that individual and we provide them all the food they need for the duration of the study,” she said.
“It has been a huge learning curve as we have developed new tools to capture the dietary data, to analyse it digitally, allowing us to time-stamp eating occasions throughout the day, with a particular emphasis on the quantity, quality and timing of food relative to a specific training stimulus. We have coined the phrase ‘peri-training nutrition’ to describe this. With that information, we can see minute by minute, in some instances, how diet affects recovery, how well the muscles ‘refuel’ after training and, over the long term, how muscle mass and even bone mass changes.”
Water and dairy
While Norton is currently working with highly trained athletes, she has sage advice for those of us who might be considering taking up or boosting our exercise regimes in the new year.
“Most people who take up a new exercise are focused on health and wellbeing rather than silverware, and it’s good to think about the best option for supporting that with nutrition,” she said.
“You don’t need expensive isotonic drinks and protein supplements if you are starting out with running or resistance training. Drink water to keep hydrated, and dairy is an excellent source of protein in terms of availability and cost.”
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