Biomechanics, energetics and coordination during extreme swimming intensity: effect of performance level

Abstract

The present study aimed to examine how high- and low-speed swimmers organise biomechanical, energetic and coordinative factors throughout extreme intensity swim. Sixteen swimmers (eight high- and eight low-speed) performed, in free condition, 100-m front crawl at maximal intensity and 25, 50 and 75-m bouts (at same pace as the previous 100-m), and 100-m maximal front crawl on the measuring active drag system (MAD-system). A 3D dual-media optoelectronic system was used to assess speed, stroke frequency, stroke length, propelling efficiency and index of coordination (IdC), with power assessed by MAD-system and energy cost by quantifying oxygen consumption plus blood lactate. Both groups presented a similar profile in speed, power output, stroke frequency, stroke length, propelling efficiency and energy cost along the effort, while a distinct coordination profile was observed (F = 3.59, P = 0.04). Speed, power, stroke frequency and propelling efficiency (not significant, only a tendency) were higher in high-speed swimmers, while stroke length and energy cost were similar between groups. Performing at extreme intensity led better level swimmers to achieve superior speed due to higher power and propelling efficiency, with consequent ability to swim at higher stroke frequencies. This imposes specific constraints, resulting in a distinct IdC magnitude and profile between groups.

Dynamics of the Metabolic Response During a Competitive 100-m Freestyle in Elite Male Swimmers

“…21 In parallel with these reductions, Etot increased between 25 and 50 m but then decreased markedly by ~20% in the last 50 m compared with the first 50 m. This change is likely related to the rapid decrease of Ean,al (muscle PCr is depleted in ~10-s) and the fast V O2 kinetics. 16,19 This pattern is consistent with the adaptive dynamics of the metabolic energy chains generally observed during supramaximal exercise of similar duration. 1 Our data showed that O2 increased rapidly and reached its maximal value at 50 m. The O2 kinetics from the first 30-s of exercise (up to 4.2 ± 0.7 l•min -1 ) appeared faster than that observed by Jalab et al 5 in swimmers with a lower performance level who only reached their peak O2 after 75 m. The time constant for O2 kinetics was equal to or less than 10-15-s, consistent…”

“…with the fastest values observed in previous studies. 16,19 The high swimming speed of the faster swimmers in our study induced rapid adjustment of O2, with a near maximal fraction of O2 reached quickly. This time course of O2 increase has also been observed in other sports during all-out testing.…”

“…Total amount of metabolic energy expenditure (E tot , kJ) during each of the 100-m supramaximal swims was calculated as the sum of three terms: 2,15,16,17 E tot = E an,al + E an,lac + E aer (1) where where  is the energy equivalent of accumulated blood lactate, assumed to be 0.0689 kJ•mmol - 19 [La]b,net is the net lactate concentration in blood (mmol•l -1 ), assuming a resting value of 1.5 mmol•l -1 , and Mb (kg) is the swimmer's body mass.…”

“…18 The Ean,al, Ean,lac and Eaer contributions for each lap were then calculated as the difference in these three terms before and after each lap. 19 For the whole 100-m, the alactic anaerobic, lactic anaerobic and aerobic powers [Ean,al, Ean,lac and Eaer (kW] were calculated by dividing the total energy (kJ) by the 100-m time.…”

In-Water and On-Land Swimmers’ Symmetry and Force Production

“…Biomechanical characteristics are important swimming performance determinants, fundamental in understanding propulsion mechanics in the highly specific hydrodynamic environment. Analyzing swimmers' force production should be a priority in their training control and research, as an effective propulsion is fundamental for competitive success [1][2][3]. For this purpose, tethered swimming has been one of the most frequently used methods, yielding substantial associations between tethered forces and swimming performance in sprint events [4][5][6].…”