I'm looking for suggestions for a 60-90 minute session, complete with exercises, sets, weight, rep, etc.
My primary goal is to build speed for 5k trail races.
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I can only offer this as to what worked for me. I ran 5k and 800m competitively in high school and college, and then moved onto half marathons before getting out of competitive running entirely.
When I started strength training during running I felt a lot more "stable" on my runs.
I know that endurance and speed increase by running longer and running faster, but I anecdotally I found increases in my overall leg control and stability. When coming down on a weird landing, or just basically anything other than a simple straight forward stride, my legs tended to be a lot more solid. If you can imagine that legs-crumble feeling you get at the end of a race or when landing weird, I was able to delay/minimize that.
With no particular evidence to back up why, I was doing this (half marathon training):
So boiled down I was lifting twice a week, running thrice a week, and still managing one full day off and one day of yoga.
I also experimented with doing my lifts after my runs (same day), which actually worked out better. If my legs were fried from running I wouldn't hit the squats that hard, but because I was keeping the weight fairly light I never really had any problems meeting it. I opted to combine my running and lifting days once the mileage/speed got to the point that I needed more dedicated days off.
One big piece of advice I can offer though is to use the time now to learn the proper compound barbell lifts. Fundamentally a proper back squat is a proper back squat, regardless of whether it's high reps and low weight for a runner's training or it's some huge monster pushing 900lb.
Even if you're not doing a "real strength training program" (which are awesome, honestly), it doesn't mean you can't use the same movements and get them dialed in. At some point in your life you'll be really happy you have dialed in form on the "big lifts".
Also, as you near race day, cut the weights out the week in advance. Drop the mileage, drop the speed, and keep fresh.