University of Jyväskylä

Dissertation: 21.4.2018 Dietary acid load and acid-base balance in exercise and health from adolescence to late adulthood (Hietavala)

Start date: Apr 21, 2018 12:00 PM

End date: Apr 21, 2018 03:00 PM

Location: Seminaarinmäki, L304

Enni-Maria Hietavala. Photo by Saara Åhlgrén
M.Sc. (Sport Sciences) Enni-Maria Hietavala defends her doctoral dissertation in Exercise Physiology "Dietary acid load and acid-base balance in exercise and health from adolescence to late adulthood". Opponent Professor Lars MgNaughton (Edge Hill University, UK) and Custos Professor Antti Mero (University of Jyväskylä). The doctoral dissertation is held in English.

This thesis investigated whether dietary acid load has either short-term (4 to 7
days) or prolonged (12 weeks) effects on acid-base status at rest and during
submaximal and maximal aerobic exercise; whether the effects of dietary acid
load on acid-base status differ between adolescents, young adults and the
elderly, and between men and women; and whether the changes in acid-base
balance have a further effect on aerobic exercise performance.

These questions  were addressed in three different study settings in healthy and recreationally active men and women. In studies 1 and 2, which followed a crossover study
design, participants were assigned in randomized order to follow a diet with a
low or high acid load for 4 or 7 days. Study 3 was a 12-week longitudinal study
in which participants were divided into two groups of lower and higher acid

Nine 18- to 30-year-old men participated in study 1. In study 2, 93 men
and women were recruited from three age groups: 12 to 15 years, 25 to 35 years
and 60 to 75 years. Forty-nine men and women aged 20 to 50 years participated
in study 3.

The main finding was that dietary acid load has acute and prolonged
effects on blood and urine acid-base status and may also have effects on
exercise performance. In young and elderly women, in particular, blood was
more acidic at rest and during submaximal cycling after a 7-day high compared
to low acid intake. In young women, maximal cardiorespiratory measures were
lower and time to exhaustion shorter after high compared to low acid intake.

During exercise, better renal function may be associated with higher
bicarbonate ion availability in blood, which can diminish exercise-induced
acidosis and delay fatigue. Lower kidney function in the elderly compared to
younger participants, and in women compared to men may explain why the
diet-induced changes in blood acid-base status were greater in the elderly
participants and in women compared to younger participants and men.

Moreover, even slightly acidogenic diets combined with regular training may
be accompanied with increased acid load to the body and start to impair kidney
function. These results emphasize the importance of an adequate intake of fruits
and vegetables as a part of a healthy diet and a physically active lifestyle across
the lifespan.

More information

Enni-Maria Hietavala
040 805 4733
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