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- Longitudinal changes in force production of young competitive swimmers: assessment tools for training control and optimizationPublication . Santos, Catarina Maria Simões da Costa; Marinho, Daniel Almeida; Costa, Mário Jorge de OliveiraThe general purpose of this thesis was to analyze the changes in force production of young competitive swimmers during a full competitive season and over a detraining period. Simultaneously, there was an attempt to understand if a two-hand pressure system is a suitable tool to be used for monitoring in-water forces in swimmers from this age cohort. To support this, specific purposes were defined according to the following sequence: (i) to systematically review the available literature focusing on the human propulsive forces in swimming; (ii) to verify the reliability of a pressure sensors system; (iii) to understand if the system impairs the swimming mechanics and efficiency; (iv) to perform an agreement between available methods that measure in-water forces; (v) to determine the changes in force production of young swimmers during a competitive season; (vi) to understand how a detraining period affects in-water forces according to different maturity status. Main results suggest that: (i) there is a scarce number of studies dealing with long-term changes in-water forces of young swimmers, and the methods used for that purpose were little explored; (ii) a two-hand pressure sensors system showed to be reliable to measure in-water forces during front-crawl swimming; (iii) the system did not induced any mechanical or efficiency constraints; (iv) a correction factor is needed to compare the in-water forces obtained by different methods; (v) a full competitive season seems to promote improvements in force production along with an increase in asymmetric motion; and (vi) in-water forces seems to remain unchanged even with a six-weeks of training cessation.
- Kinetic Analysis of Water Fitness Exercises: Contributions for Strength DevelopmentPublication . Santos, Catarina; Rama, L; Marinho, Daniel; Barbosa, Tiago M.; Costa, Mário JorgeThe evaluation of propulsive forces in water allows the selection of the most appropriate strategies to develop strength during water fitness sessions. The aim of this study was threefold: (i) to analyze the rate of force production; (ii) to analyze the rate of force variation; and (iii) to compare limbs' symmetry in two water fitness exercises. Twenty-two young health subjects (age: 21.23 ± 1.51 years old, body mass: 67.04 ± 9.31 kg, and height: 166.36 ± 8.01 cm) performed incremental protocols of horizontal adduction (HA) and rocking horse (RHadd), from 105 until 150 b·min-1. Data acquisition required an isokinetic dynamometer and a differential pressure system that allowed the assessment of (a) isometric peak force of dominant upper limb (IsometricFD); (b) propulsive peak force of dominant upper limb (PropulsiveFD); and (c) propulsive peak force of nondominant upper limb (PropulsiveFND). Significant differences were found in the rate of force production (RateFD) between the majority cadences in both exercises. The RateFD reached ~68% of the force in dry-land conditions, and lower cadences promoted a higher rate of force variation (ΔForce). Most actions were asymmetric, except for the HA at 135 b·min-1. In conclusion, the musical cadence of 135 b·min-1 seems to elicit a desired rate of force production with a symmetric motion in both exercises.