Effects of caffeine drinks on endurance performance, fluid balance and subjective feelings

Abstract

Int J Sport Nutr Exe Metab 2013, 23, (5 Supplement)

The use of energy drinks before an acute exercise among recreational athletes has been observed to increase in order to enhance well-being. This study compared the acute effect of energy drinks on fluid balance and subjective feelings during endurance exercise.

Healthy adults (N=10, 5 men, 5 women, 26±8 years) completed four endurance exercises (randomized, crossover) in warm 22˚C temperature while ingesting 25 min before each trial one service (0.33 L) of 1) high CHO (33 g) energy drink with 106 mg caffeine (HCHO), 2) low CHO (10 g) energy drink with 106 mg caffeine (LCHO), 3) low CHO non-caffeine drink (NCAF) or 4) water (WAT). Trials were separated by seven days. Endurance exercise included 60 min cycling at 60 % of VO2max (SUBMAX) and then an incremental test to exhaustion (MAX). Blood samples for lactate, glucose, osmolality, Na+, Cl- and K+ were drawn before drink and immediately before and after SUBMAX. Urine Na+, K+, osmolality and specific gravity were also analyzed. Food ingestion was standardized 16 h before each trial.

Heart rate, rate of perceived exertion and blood lactate increased during SUBMAX, but there were no significant differences between the trials. In addition, all trials induced a similar increase in serum osmolality and Na+, K+ and Cl- concentrations and decrease in urine osmolality and Na+ concentration in response to SUBMAX. Urine K+ remained the same. Furthermore, there were no differences between the trials in MAX time to exhaustion (LCHO 7:34±1:53, NCAF 7:08±1:19, HCHO 8:07±2:33, WAT 6:57±1:36 min:sec, P>0.05) and changes in body weight and plasma volume. However, thirst (P<0.05) and plasma glucose (P<0.001) had a significant exercise x trial interaction increasing first after ingestion HCHO and LCHO and decreasing in the middle of SUBMAX.

In conclusion, caffeinated energy drink with high or low carbohydrate and non-caffeine or pure water before an acute endurance exercise had similar effects on fluid balance and subjective feelings and endurance performance.

Full text

DEPARTMENT OF BIOLOGY OF PHYSICAL ACTIVITY
International Sport & Exercise Nutrition Conference, 13.-15.12.2012, Newcastle, GB.
EFFECTS OF CAFFEINE DRINKS ON ENDURANCE PERFORMANCE,
FLUID BALANCE AND SUBJECTIVE FEELINGS
METHODS
Subjects
• Healthy recreational athletes.
• N=10, 5 men and 5 women, aged 26±8 years.
Performance and subjective feelings
• Maximal aerobic tness test (VO2max) until volutary
exhaustion on ergometer to dene workload for SUBMAX.
• Endurance exercise included 5 min warm-up (40W for women,
50W for men), 60 min cycling at 60 % of VO2max (SUBMAX) and
incremental test to exhaustion (MAX).
• During the endurance exercise rate of perceived exertion (RPE,
scale 6-20) and feelings of thirst (0-7 Likert scale) was asked and
heart rate (HR), blood lactate (La) and glucose (glu) measured.
(Figure 1).
Randomized, crossover protocol
Subjects performed four endurance exercises (SUBMAX+MAX)
separated by seven days in warm 22˚C temperature while
ingesting 25 min before each trial one service (0.33 L) of :
1) High CHO (33 g) energy drink with 106 mg caffeine (HCHO)
2) Low CHO (10 g) energy drink with 106 mg caffeine (LCHO)
3) Low CHO (10 g) non-caffeine drink (NCAF) or
4) Water (WAT)
Food ingestion was standardized 16 h before each trial.
In the middle of the each trial subjects ingested 1 dL of water.
Fluid and electrolyte balance
• Serum sodium Na+, potassium K+, chloride Cl- and osmolality
• Urine Na+, K+, Cl-, osmolality and specic gravity
• Change in plasma volume was calculated from changes in
hemoglobin and hematocrit (Dill and Costill 1974).
• Changes in body mass
See study design Figure 1.
INTRODUCTION
The use of caeinated energy drinks
before an acute exercise among
recreational athletes has observed to
increase in order to enhance well-being.
To evaluate the acute eect of energy
drinks on endurance performance, uid
and electrolyte balance and subjective
feelings.
PURPOSE
Minna Tanskanen, Tuomo Heikkinen, Vesa Linnamo
Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland
Performance
• HR and La (Figure 2) increased during endurance exercise, but
there were no differences between the trials.
• There were no differences between the trials in MAX time to
exhaustion (LCHO 7:34±1:53, NCAF 7:08±1:19, HCHO 8:07±2:33,
WAT 6:57±1:36 min:sec, p>0.05) .
RESULTS
CONCLUSION
Caeinated energy drink with
high or low carbohydrate and
non-caeine or pure water
before an acute endurance
exercise have similar eects on
uid balance and subjective
feelings and endurance
performance.
The study was granted by the Oy Sinebrychoff Ab .
Body mass, plasma volume and blood glucose
• Ther were no differences between the trials in changes in body
mass (mean -1.3±0.3 %) and plasma volume (mean -9.1±3.7 %).
• Blood glucose (P<0.001) had a signicant exercise x drink
interaction increasing rst after ingestion HCHO and LCHO and
decreasing in the middle of SUBMAX (Figure 4).
Subjective feelings
• RPE (Figure 3a) increased during SUBMAX, but there were no
differences between the trials.
• Feelings of thirst (Figure 3b) had a signicant exercise x drink
interaction (p<0.05) increasing rst after ingestion HCHO and
LCHO and decreasing in the middle of SUBMAX, while WAT
induced an increase in thirst in the middle.
80
100
120
140
160
warm-up 0-10 10-20 20-30 30-40 40-50 50-60
(bpm)
LCHO
NCAF
HCHO
WAT
exercise p<0.001
drink p=0.555
exercise x drink p=0.133
0
2
4
6
8
10
PRE 1 PRE 2 MID POST 1 POST 2
(mmol/l)
LCHO
NCAF
HCHO
WAT
exercise p <0.001
drink p = 0.095
exercise x drink p = 0.176
6
8
10
12
14
16
18
warm-up 15 min 30 min 45 min 60 min
LCHO
NCAF
HCHO
WAT
exercise p<0.001
drink p=0.076
exercise x drink p=0.111
0
1
2
3
4
5
6
7
warm-up 15 min 30 min 45 min 60 min
LCHO
NCAF
HCHO
WAT
exercise p<0.001
drink p=0.981
exercise x drink p=0.027
FIGURE 1. Study design. Blood = venous blood sample
-60 0
(min) 10 20 45 75 80 115 145
PRE 1 PRE 2 MID POST 1 POST 2
MAX
La, glu
La, glu
La, glu
Blood Blood Blood Urine Body
mass
SUBMAX
Breakfast
or snack
Body
mass
Urine Drink La,
glu
La,
glu
a) HR b) La
a) RPE b) Thirst
Fluid and electrolyte balance
• All trials induced a similar increase in serum osomolality
and Na+, K+ and Cl- concentrations.
• All trials induced a similar decrease in urine osomolality and
Na+ concentration.
• Urine K+ remained the same.
• There were no differences between the trials in urine
specic gravity before the endurance exercise and no
diffrerences in decrease due the endurance exercise.
FIGURE 2. HR (a) and blood La (b) during the endurance exercise. HR is ex-
pressed as an average at dierent time periods.
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
PRE 1 PRE 2 MID POST 1 POST 2
(mmol/l)
LCHO
NCAF
HCHO
WAT
exercise p<0.001
drink p<0.001
exercise x drink p<0.001
FIGURE 3. RPE (a) and subjective feelings of thirst (b) during the endurance ex-
ercise.
FIGURE 4. Blood glucose concentra-
tions during the endurance exercise.