Table 1

Characteristics of the studies included in the systematic review and meta-analysis

Study, year	Design	Subjects: n, sex, age, years±SD or range	Fitness	Intervention	Outcomes
Molphy et al, 201958	Three-way cross-over	16, M/F 8/8, 23±3	Recreationally active >2 times/week	Inhaled terbutaline 2000 μg Inhaled terbutaline 4000 µg	3000 m treadmill time trial
Merlini et al, 201957	Cross-over	13, M, 18±1	Amateur football	Inhaled salbutamol 1600 μg	Shuttle run test
Hafedh et al, 201956	Cross-over	12, 6/6, 22±1	Recreationally active	Oral terbutaline 8000 µg	Shuttle run test
Laurent et al, 201855	Three-way cross-over	14, M, 25±5	Endurance athletes 6±2 hours/week	Inhaled salbutamol 800 µg Oral salbutamol 4000 µg	Quadriceps contractions to task failure
Eckerström et al, 201854	Cross-over	36, M/F 18/18, 26±5	Non-athletes	Inhaled salbutamol 900 µg	VO_2max
Molphy et al, 201753	Three-way cross-over	7, M, 22±1	Recreational exercise ≥3 hours/week	Inhaled salbutamol 400 µg	3000 m treadmill time trial
Halabchi et al, 201752	Cross-over	20, M, 17±1	Junior professional football players	Inhaled 200 µg salbutamol	20 m multistage shuttle run test
Hostrup et al, 201662	Parallel	20, M, 26±4	National level endurance athletes*	Oral salbutamol 8000 µg acute and 8000 µg/day for 2 weeks	VO_2max, time to exhaustion
Koch et al, 201551	Cross-over	35, M, 28±5	Experienced cyclists/triathletes, VO_2max ≥60 mL/kg/min or 5 L	Inhaled salbutamol 400 µg	10 km ergometer time trial
Koch et al, 201550	Cross-over	15, F, 30±5	Cyclists and triathletes VO_2max 50 mL/kg/min or 4 L	Inhaled salbutamol 400 µg	10 km ergometer time trial
Koch et al, 201549	Cross-over	12, M, 31±7	Competitive cyclists VO_2max ≥60 mL/kg/min or 5 L	Inhaled salbutamol 1600 μg	10 km ergometer time trial
Hostrup et al, 201561	Parallel	18, M, 24±3	Recreationally active 4–8 hours/week	Oral terbutaline 5000 µg/30 kg body weight, two times per day for 28±1 days	VO_2max, cycling to exhaustion, incremental
Kalsen et al, 201448	Cross-over	9, M, 24±3	Moderately trained	Inhaled terbutaline 15 000 µg	300 kcal cycling time trial
Hostrup et al, 201447	Cross-over	9, M, 24±3	Recreationally active	Inhaled terbutaline 15 000 µg	100 kcal cycling time trial
Dickinson et al, 201460	Parallel	16, M, 20±2	Amateur-level competition	Inhaled salbutamol 1600 µg/day for 6 weeks	V̇O_2peak, 3 km treadmill time trial
Dickinson et al, 201446	Three-way cross-over	7, M, 22±4	Runners, >2 times/week	Inhaled salbutamol 800 µg and 1600 µg	5 km treadmill time trial in 18°C and 30°C
Sanchez et al, 201345	Cross-over	7, M, 29±6	Competitive recreational athletes, 10 hours/week	Oral terbutaline 8000 µg	Cycling to exhaustion, VO_2max
Decorte et al, 201344	Three-way cross-over	11, M, 33±6	Highly trained cyclists/triathletes/runners, 12±3 hours/week*	Inhaled salbutamol 200 µg and 800 µg	Quadriceps contractions to task failure
Elers et al, 201243	Cross-over	9, M, 27±5	Endurance-trained 11 hours/week*	Inhaled 8000 µg salbutamol	Peak power output, incremental VO_2max
Beloka et al, 201142	Cross-over	21, M, 23±2	Healthy non-athletes	Infused salbutamol 350 µg or 700 µg	VO_2max
Andersen and Kanstrup, 200941	Cross-over	7, M, 25, 18–30	Highly endurance-trained*	Oral salbutamol 4000 µg	Running to exhaustion, VO_2max
Sporer et al, 200840	Four-way cross-over	27, M, 29±6	Competitive cyclists and triathletes*	Inhaled salbutamol 200 µg, 400 µg and 800 µg	20 km cycling time trial
Decorte et al, 200839	Three-way cross-over	10, M, 23±3	Healthy non-athletes	Inhaled salbutamol 200 µg and 800 µg	Cycling to exhaustion, incremental, VO_2max
Tjørhom et al, 200738	Cross-over	23, M, 29±5	Endurance athletes, VO_2max 60.6 mL/kg/min	Inhaled formoterol 18 µg	Running to exhaustion at −20°C at 107% VO_2max, VO_2max
Riiser et al, 200637	Cross-over	20, M, 29±4	Endurance athletes, VO_2max 61.1 mL/kg/min	Inhaled formoterol 18 µg	Running to exhaustion in hypobaric conditions at 107% VO_2max, VO_2max
van Baak et al, 200436	Cross-over	16, M, 23±3	Cyclists and triathletes, training 11±3 hours/week*	Inhaled 800 µg salbutamol	Cycling time trial
Stewart et al, 200235	Three-way cross-over	10, M, 26, 20–30	Highly trained athletes*	Inhaled formoterol 12 µg or inhaled salbutamol 400 µg	VO_2max
Collomp et al, 200234	Cross-over	8, M, 26±2	Moderately trained	Oral salbutamol 6000 µg	10 min cycling time trial
Collomp et al, 200029	Cross-over	9, M, 25±1	Moderately trained	Oral salbutamol 6000 µg	Cycling to exhaustion at 85% of VO_2max
Collomp et al, 200030	Cross-over	8, M, 23±3	Recreational athletes, cycling/running 3–5 times/week	Oral salbutamol 12 000 µg/day for 3 weeks	Cycling to exhaustion at 85% of VO_2max
Goubault et al, 200133	Three-way cross-over	13, M, 23±2	Competitive triathlete	Inhaled salbutamol 200 µg and 800 µg	Cycling to exhaustion at 85% of VO_2max
Carlsen et al, 200132	Cross-over	24, M, 25±3	Competitive athletes*	Inhaled formoterol 9 µg	Running to exhaustion at 105% of VO_2max VO_2max
van Baak et al, 200031	Cross-over	16, M, 23±2	Healthy non-athletes	Oral salbutamol 4000 µg	Cycling to exhaustion at 70% of VO_2max
Sue-Chu et al, 199928	Cross-over	8, M, 19–28	Highly trained cross-country skiers*	Inhaled salmeterol 50 µg	Running to exhaustion at −15°C, incremental VO_2max
Sandsund et al, 199827	Cross-over	8, M, 25±4	Highly trained cross-country skiers*	Aerosolised salbutamol 1200 µg	Running to exhaustion, incremental, VO_2max
Larsson et al, 199726	Cross-over	20, M, 24, 18–31	Elite endurance athletes*	Inhaled terbutaline 3000 µg	Running to exhaustion, incremental, VO_2max
Carlsen et al, 199725	Three-way cross-over	18, M, 23±6	Running >3 times/week	Inhaled salbutamol 800 µg Inhaled salmeterol 50 µg	Running until exhaustion, incremental, VO_2max
Norris et al, 199624	Cross-over	15, M, 25±4	Highly trained cyclists	Inhaled 400 µg salbutamol	20 km cycling time trial VO_2max
Heir and Stemshaug, 199523	Cross-over	17, M, 18–30	Highly conditioned endurance athletes*	Aerosolised salbutamol 50 µg/kg	Running to exhaustion at 110% VO_2max, VO_2peak
Unnithan et al, 199422	Cross-over	10, M, 10±1	Healthy non-athletes	Inhaled terbutaline 500 µg	Total running time VO_2peak
Fleck et al, 199321	Cross-over	21, M, 24±5	Elite cyclists	Inhaled salbutamol 360 µg	W-max VO_2max
Morton et al, 199220	Cross-over	17, M/F 16/1, 22±4	High-performance runners*	Inhaled salbutamol 200 µg	Running to exhaustion, incremental VO_2max
Meeuwisse et al, 199219	Cross-over	7, M, 24±4	Trained cyclists	Inhaled salbutamol 200 μ g	Endurance sprint time VO_2max
Violante et al, 198918	Cross-over	7, M, 34±8	Sedentary non-athletes	Intravenous salbutamol 4 µg/kg followed by 3 µg/kg/hour	Walking to exhaustion, incremental
Bedi et al, 198816	Cross-over	15, M/F 14/1, 23±5	Cyclists, triathletes	Inhaled salbutamol 180 µg	Cycling to exhaustion after 60 min submaximal exercise VO_2max
Booth, 198817	Cross-over	10, F, 21±7	Trained cyclists	Inhaled salbutamol ×2, therapeutic dose	Cycling to exhaustion
McKenzie et al, 198359	Parallel	4, M, 25±8 5, F, 27±10 5, M, 24±9 5, F, 26±13	Highly trained track and field athletes*	Inhaled salbutamol 800 µg	VO_2max

*Denotes high-performance endurance athletes.
F, female; M, male; VO_2max, Maximal oxygen consumption; W-max, maximal workload during incremental cycling.