Swimming is a way to maintain a streamlined body position, which requires core muscle strength; the core muscles must be strong to carry out their function in maintaining body position during swimming. Core muscle strength correlates with swimmers' buoyancy and performance. Thus, training such as core stability exercises is needed to increase the strength of the core muscles. Therefore, this study aims to determine the effectiveness of core stability exercises using a Swiss ball to increase core muscle strength in junior swimmers. An experimental method was employed with one group only pretest and posttest design. The research instrument utilized to measure the core muscle strength of junior swimmers was the sit-up test. 50 members of the Taksaka Swimming Club were determined as the population of the study while only 30 of them were involved as the sample of this study. Out of the 30 people, 15 of them were given treatment and the rest 15 people were grouped in the control group. They were divided using a purposive sampling technique. The results showed that core stability exercise using a Swiss ball was effective in increasing core muscle strength in junior swimmers as indicated by a t-score of 7.5 at the significance level of α = 0.05. Therefore, it can be concluded that core stability exercises using a Swiss ball can be used to increase the strength of the core muscles to enable the stability around the lumbar spine and abdominal muscles might bring about biomechanical changes that allow swimmers to swim faster in a more efficient way.

Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh latihan SAQ (Speed, Agility, Quickness) terhadap peningkatan kelincahan atlet bulutangkis kelompok umur ganda remaja puteri PB. Djarum.Teknik yang digunakan dalam pengambilan sampel adalah total sampling sehingga sampel yang digunakan berjumlah 8 orang.Instrumen penelitian yang digunakan dalam penelitian ini adalah Court Agility Test. Hasil perhitungan mengenai tes awal dan tes akhir Court Agility Test diperoleh data sebagai berikut : selisih rata-rata (MD) 1,20 dengan standar deviasi perbedaan (SDD) 0,55, standar error perbedaan rata-rata (SEMD) 0,21 dalam perhitungan selanjutnya diperoleh nilai t-hitung sebesar 5,71 dan nilai t-tabel dengan derajat kebebasan (n-1) = 7 dan taraf signifikan α = 0,05 didapat sebesar 2,81 yang berarti t-hitung = 5,71 lebih besar dari t-tabel = 2,81. Hal ini menunjukkan bahwa hipotesis nihil (H0) ditolak dan hipotesis alternatif (Hi) diterima. Dengan demikian hasil perhitungan tersebut menyatakan bahwa : latihan SAQ (Speed, Agility, Quickness) berpengaruh signifikan terhadap peningkatan kelincahan atlet bulutangkis kelompok umur ganda remaja puteri PB. Djarum.