Physical fitness plays an important role in supporting student performance, especially in the health sector, which demands optimal physical condition and stamina. The purpose of this study was to analyze the effect of aerobic exercise on improving physical fitness in Nursing Assistant program students at SMK Kesehatan Bhakti Kencana Subang. The study design used a quasi-experimental model with a One Group Pretest-Posttest. Twenty students became the research sample, selected through a purposive sampling technique. The level of physical fitness was measured using the Multistage Fitness Test (Bleep Test) to estimate the VO? Max value. The intervention in the form of aerobic exercise was carried out for 4 weeks, with a frequency of three times a week and a duration of 45 minutes per session. Data analysis used a Paired Sample t-test. The results showed that the average VO? Max before treatment was 36.5 ml/kg/min (moderate category), increasing to 42.8 ml/kg/min (good category) after treatment, with a difference in increase of 6.3 ml/kg/min. The statistical test yielded a p-value of 0.000 (p < 0.05), indicating a significant difference between pre- and post-exercise conditions. This improvement is influenced by the body's physiological adaptations to regular aerobic exercise, such as increased lung capacity, heart strength, and muscle efficiency. Thus, aerobic exercise has been proven effective in improving the physical fitness of Nursing Assistant students and is beneficial for supporting their physical health and academic performance. ABSTRAKKebugaran jasmani memiliki peran penting dalam mendukung performa siswa, khususnya pada bidang kesehatan yang menuntut kondisi fisik dan stamina optimal. Tujuan penelitian ini yaitu untuk menganalisis pengaruh latihan dari senam aerobik terhadap peningkatan kebugaran jasmani pada siswa program Asisten Keperawatan di SMK Kesehatan Bhakti Kencana Subang. Rancangan penelitian menggunakan quasi experiment dengan model One Group Pretest-Posttest. Dua puluh siswa menjadi sampel penelitian, dipilih melalui teknik purposive sampling. Tingkat kebugaran jasmani diukur menggunakan Multistage Fitness Test (Bleep Test) untuk memperkirakan nilai VO? Max. Intervensi berupa latihan senam aerobik dilakukan selama 4 minggu, dengan frekuensi tiga kali dalam seminggu dan durasi 45 menit setiap sesi. Analisis data menggunakan uji Paired Sample t-test. Hasil penelitian menunjukkan rata-rata VO? Max sebelum perlakuan sebesar 36,5 ml/kg/min (kategori sedang), meningkat menjadi 42,8 ml/kg/min (kategori baik) setelah perlakuan, dengan selisih peningkatan 6,3 ml/kg/min. Uji statistik menghasilkan nilai p = 0,000 (p < 0,05), yang menandakan adanya perbedaan signifikan antara kondisi sebelum dan sesudah latihan. Peningkatan tersebut dipengaruhi oleh adaptasi fisiologis tubuh terhadap latihan aerobik rutin, seperti meningkatnya kapasitas paru-paru, kekuatan jantung, serta efisiensi kerja otot. Dengan demikian, senam aerobik terbukti efektif dalam meningkatkan kebugaran jasmani siswa Asisten Keperawatan dan bermanfaat untuk menunjang kesehatan fisik maupun performa akademik mereka