title: Plasma K+ dynamics and implications during and following intense rowing exercise.
abstract: We investigated whether potassium (K(+)) disturbances during and following intense exercise may be pronounced when utilizing a large contracting muscle mass, examining maximal 2,000-m rowing exercise effects on radial arterial plasma K(+) concentration ([K(+)]a) in 11 healthy adults. Blood was sampled at baseline, preexercise, each 30 s during rowing, and for 30 min postexercise. Time to complete 2,000 m was 7.26 ± 0.59 min; power output at 30 s was 326 ± 81 W (mean ± SD). With exercise time expressed in deciles, power output fell 16.5% from the first to fourth decile (P < 0.05) and 19.9% at the ninth decile (P < 0.05); EMG median frequency declined 4.6% by the third decile and 5.5% by the eighth decile (P < 0.05). Plasma [K(+)]a increased from 3.89 ± 0.13 mM at rest to 6.13 ± 0.46 mM by 90 s rowing (P < 0.001) and was then sustained until end exercise (P < 0.001). In recovery, [K(+)]a decreased abruptly, reaching 3.33 ± 0.22 mM at 5 min postexercise (P < 0.001) and remaining below preexercise after 30 min (P < 0.005). At end exercise, blood [lactate]a (preexercise 0.64 ± 0.18 mM) reached 10.87 ± 1.33 mM, plasma volume decreased 9.7 ± 2.3% from preexercise, and pHa decreased to 7.10 ± 0.07 units (P < 0.001). In conclusion, arterial hyperkalemia was sustained during exhaustive rowing reflecting a balance between K(+) release and reuptake in contracting muscles and K(+) uptake by inactive muscles. While high, the [K(+)]a was lower than anticipated compared with maximal cycling or sprinting, possibly reflecting greater adrenergic response and Na(+),K(+)-ATPase activity in contracting muscles; fatigue was evidenced by reduced power output and EMG median frequency. A prolonged hypokalemia after rowing likely reflected continuing muscular Na(+),K(+)-ATPase activity.
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia;
authors.forename: Tania
authors.initials: T
authors.lastname: Atanasovska
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia;
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Petersen
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; Australian Institute of Sport, Canberra, Australia;
authors.forename: David M
authors.initials: DM
authors.lastname: Rouffet
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; Institut National du Sport du Québec, Montréal, Quebec, Canada; and.
authors.forename: François
authors.initials: F
authors.lastname: Billaut
authors.affiliation: Department of Anaesthesia, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.
authors.forename: Irene
authors.initials: I
authors.lastname: Ng
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; michael.mckenna@vu.edu.au.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKenna
mesh_terms: D000328:Adult; D001158:Arteries / Q000378:metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D010953:Plasma Volume / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D055815:Young Adult
chemical_list: D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium
keywords: exercise; hyperkalemia; hypokalemia; muscle fatigue; potassium