We　employed　near-infrared　optical　techniques,　diffuse　correlation　spectroscopy　(DCS),　and　frequency-domain　nearinfrared　spectroscopy　(FD-NIRS)　to　test　the　hypothesis　that　supervised　exercise　training　increases　skeletal　muscle　microvascular　blood　flow　and　oxygen　extraction　in　patients　with　peripheral　artery　disease　(PAD)　who　experience　claudication.　PAD　patients　(n　=　64)　were　randomly　assigned　to　exercise　and　control　groups.　Patients　in　the　exercise　group　received　3　mo　of　supervised　exercise　training.　Calf　muscle　blood　flow　and　oxygen　extraction　were　optically　monitored　before,　during,　and　after　performance　of　a　graded　treadmill　protocol　at　baseline　and　at　3　mo　in　both　groups.　Additionally,　measurements　of　the　ankle-brachial　index　(ABI)　and　peak　walking　time　(PWT)　to　maximal　claudication　were　made　during　each　patient　visit.　Supervised　exercise　training　was　found　to　increase　the　maximal　calf　muscle　blood　flow　and　oxygen　extraction　levels　during　treadmill　exercise　by　29%　(13%,　50%)　and　8%　(1%,　12%),　respectively　[P　＜　0.001;　median　(25th　percentile,　75th　percentile)].　These　improvements　across　the　exercise　group　population　were　significantly　higher　than　corresponding　changes　in　the　control　group　(P　＜　0.004).　Exercise　training　also　increased　PWT　by　49%　(18%,　101%)　(P　＜　0.01).　However,　within　statistical　error,　the　ABI,　resting　calf　muscle　blood　flow　and　oxygen　extraction,　and　the　recovery　half-time　for　hemoglobin\myoglobin　desaturation　following　cessation　of　maximal　exercise　were　not　altered　by　exercise　training.　The　concurrent　monitoring　of　both　blood　flow　and　oxygen　extraction　with　the　hybrid　DCS/FD-NIRS　instrument　revealed　enhanced　muscle　oxidative　metabolism　during　physical　activity　from　exercise　training,　which　could　be　an　underlying　mechanism　for　the　observed　improvement　in　PWT.　NEW　&　NOTEWORTHY　We　report　on　noninvasive　optical　measurements　of　skeletal　muscle　blood　flow　and　oxygen　extraction　dynamics　before/during/after　treadmill　exercise　in　peripheral　artery　disease　patients　who　experience　claudication.　The　measurements　tracked　the　effects　of　a　3-mo　supervised　exercise　training　protocol　and　revealed　that　supervised　exercise　training　improved　patient　ability　to　increase　microvascular　calf　muscle　blood　flow　and　oxygen　extraction　during　physical　activity.