The assessment of blood lactate concentration is considered essential for the physiological diagnosis of swimming performance. But for a more detailed and complete analysis of a swimmer's strengths and weaknesses, it is also important to examine his or her technical characteristics. However, few studies have combined physiological and technical evaluation in child swimmers. The aim of the present study was to assess the metabolic anaerobic threshold (blood lactate concentration and corresponding swimming velocity) of 10-to 11-year-old swimmers (n015) using an individualized intermittent incremental protocol. Comparison was made with the traditionally used 4 mmol × l (1 lactate threshold. In addition, stroke rate, stroke length, and stroke index were measured throughout the experimental protocol for assessment of the anaerobic threshold. Each swimmer performed a front crawl 5 )200 m test, in which the swimming velocity was controlled by an acoustic signal each 50 m. Blood samples were collected from the ear lobe (Lactate Pro, Arkay, Inc., Kyoto, Japan), at rest and after each step. Stroke rate was registered by a Seiko base 3 chronofrequencemeter; stroke length, stroke index, and velocity were calculated at the end of each 200 m. The individual anaerobic threshold occurred at 2.3 mmol × l (1 (s 00.59), and the corresponding velocity was 1.026 m × s (1 (s 00.053), much lower than the traditionally used 4 mmol × l (1 value (or even 3.5 mmol × l (1 ). The velocity corresponding to 4 mmol × l (1 and 3.5 mmol × l (1 was 1.081 m × s (1 (s 00.056) and 1.067 m × s (1 (s00.055), respectively. Stroke rate increased and stroke length decreased throughout the incremental protocol (i.e. with increasing velocity). The stroke index showed a tendency to increase throughout the protocol, with a significant difference from the first to the second step. The velocity corresponding to 4 mmol × l (1 (and 3.5 mmol × l (1 ) does not represent the metabolic individual anaerobic threshold in trained swimmers, independently of their age, and agegroup swimmers prefer to increase their velocity through an increase in stroke rate. Thus, given the importance of developing swimming technique in age-group swimmers, coaches should implement the lengthening of swimmers' stroke cycles in their training practice routines, so that they limit the effects of reduced stroke length when velocity increases.

The assessment of blood lactate concentrations is considered one essential procedure in physiological diagnosis of swimming performance. Our purpose was to assess the metabolic anaerobic threshold of an 11 year old swimmer through an individualized intermittent incremental protocol. Complementarily, stroking parameters were also determined. The subject performed a front crawl 5 x 200 m test, being the velocity controlled by an acoustic signal. The blood samples were collected from the ear lobe at rest and after each step. Stroke rate was registered by a chronofrequencemeter base 3, and stroke length and velocity were calculated at the end of each 200 m. The individual anaerobic threshold occurred at 1.2 mmol/l, rather lower than the traditionally used 4 mmol/l value suggested for trained swimmers. The velocity corresponding to anaerobic threshold was 1.06 m/s, representing a 5 s difference in a 100 m effort comparing to the velocity of 4 mmol/l. Stroke rate increased and stroke length decreased throughout the incremental protocol, i.e., with the velocity increments. It was concluded that the velocity corresponding to 4 mmol/l does not represent the individual anaerobic threshold in this young trained swimmer, and that he prefer to increase their velocity through the raise of stroke rate. Thus, given the importance of developing swimming technique in age-group swimmers, this swimmer should implement the lengthening of his stroke cycles in the training practice routines, trying to resist to the degradation of the stroke length when velocity increases.

The assessment of blood lactate concentrations is considered one essential procedure in physiological diagnosis of swimming performance. Our purpose was to assess the metabolic anaerobic threshold of an 11 year old swimmer through an individualized intermittent incremental protocol. Complementarily, stroking parameters were also determined. The subject performed a front crawl 5 x 200 m test, being the velocity controlled by an acoustic signal. The blood samples were collected from the ear lobe at rest and after each step. Stroke rate was registered by a chronofrequencemeter base 3, and stroke length and velocity were calculated at the end of each 200 m. The individual anaerobic threshold occurred at 1.2 mmol/l, rather lower than the traditionally used 4 mmol/l value suggested for trained swimmers. The velocity corresponding to anaerobic threshold was 1.06 m/s, representing a 5 s difference in a 100 m effort comparing to the velocity of 4 mmol/l. Stroke rate increased and stroke length decreased throughout the incremental protocol, i.e., with the velocity increments. It was concluded that the velocity corresponding to 4 mmol/l does not represent the individual anaerobic threshold in this young trained swimmer, and that he prefer to increase their velocity through the raise of stroke rate. Thus, given the importance of developing swimming technique in age-group swimmers, this swimmer should implement the lengthening of his stroke cycles in the training practice routines, trying to resist to the degradation of the stroke length when velocity increases.