Sup y'all. Due to a lack of access to an indoor track this year, I've been relegated to doing my workouts on an outdoor track this winter. I've been transitioning from tempo-mode into some harder middle distance intervals, but I'm finding that I generally just feel like slow shit. The kind of effort that, in the past, would have been a 4:20-something mile is now a 4:40 mile at best. I know there's plenty of stuff out there about the effect of cold weather on standard long run type stuff, but does anyone know of any good literature on the effect of cold temps on hard, 95% maxHR type workouts? Or am I just becoming old and slow?