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.

Salbutamol effects on systemic potassium dynamics during and following intense continuous and intermittent exercise

“…The antecubital venous [K + ] reported during intense intermittent exercise varies, reaching 4.3 mM during squash (Struthers et al 1988), 5.1 mM during soccer (Krustrup et al 2006), and 5.5-6 mM during repeated intermittent sprint testing (Wylie et al 2013;Mohr et al 2011;Mohr et al 2007;Duffield and Marino 2007;Mohr et al 2006 O 2 peak for use on the same cycle ergometer in the subsequent experimental trials. All respiratory measurements were as previously described (Atanasovska et al 2014) . Heart rate and rhythm were monitored at rest and during incremental exercise using a 12-lead ECG (Model X-Scribe Stress Test System, Mortara Instrument Inc, Milwaukee, WI, USA).…”

Swimming Three Ice Miles within Fifteen Hours

“…The second important finding was that after the second Ice Mile, there was an increase of [K + ] from 5.6 mM to 6.9 mM. This could be explained by a K +shift from the muscle cells as shown in a study following intense rowing exercise where plasma [K + ] increased within the first 90 sec and remained high during the exercise (2,11,12). Another study regarding the consequences and dynamics in potassium shifts concluded that a rapid and pronounced increase of [K + ] and a substantial loss of [K + ] from the active skeletal muscle were very likely primary causes of fatigue with a fast recovery (29).…”

“…The effects of a decreased natriuresis after cold immersion and hypothermia, and changes in H + should also be considered as cause of secondary changes in pH and [K + ] (33). However, this finding requires further investigation (2,16). A systematic review of swimming-related deaths suggested that cardiac arrhythmias were the most likely etiology of a swimming-related death (1).…”

“…double crossing, 2 × 25 km, 16°C water temperature) in 2011. 2 In 2012, he completed a 6-h swim in water colder than 10°C (28). In 2015, he swam two Ice Miles in water colder than 5°C (21).…”

The blood–brain barrier—Gatekeeper to neuronal homeostasis: Clinical implications in the setting of stroke

“…As a consequence, the extracellular concentrations of ions deviate from plasma concentrations, protecting the brain against physiological or pathophysiological variations in plasma potassium, calcium and magnesium levels [16]. Indeed blood potassium concentrations can increase to >6 mM during exercise [37], while calcium and magnesium concentrations can drastically decrease during different diseases and during eclampsia [38]. A myriad of transport mechanisms acts across endothelial cells [6], and transendothelial transport through brain capillaries is generally smaller than in peripheral capillaries [39].…”